Blue Sea 300A Red Mini m-Series On/Off Battery Switch w/ Lockable Key
SKU: 47674048636

Blue Sea 300A Red Mini m-Series On/Off Battery Switch w/ Lockable Key

Sale price$51.54 Regular price$57.27
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Ships within 48 hours · Estimated delivery Jul 7 - Jul 12

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Description

Blue Sea 300A Red Mini m-Series On/Off Battery Switch w/ Lockable KeySecure High Current Switching for Marine and Vehicle Systems The Blue Sea m Series Battery Switch sets the standard for compact, high performance power isolation. Designed for marine, caravan, and RV applications, this switch manages a single battery bank, allowing users to safely disconnect power during maintenance or storage. With a continuous rating of 300 Amps, it is perfectly sized for outboards, small petrol engines, and diesel engines,

Secure High-Current Switching for Marine and Vehicle Systems

The Blue Sea m-Series Battery Switch sets the standard for compact, high-performance power isolation. Designed for marine, caravan, and RV applications, this switch manages a single battery bank, allowing users to safely disconnect power during maintenance or storage. With a continuous rating of 300 Amps, it is perfectly sized for outboards, small petrol engines, and diesel engines, providing robust power handling without the bulk of industrial-grade switches.

Integrating a battery switch is essential for preserving battery life. By turning the switch to the 'Off' position, you eliminate parasitic loads that slowly drain batteries over time. This ensures that when you return to your boat or vehicle, your power system is ready to go. Its compact form factor allows for installation in tight spaces where traditional heavy-duty switches cannot fit.

Lockable Security for Safety and Theft Prevention

A standout feature of this specific model is the lockable key mechanism. Unlike standard rotary switches, this unit includes a removable key that secures the switch in the 'Off' position. This functionality provides two critical benefits: enhanced security and maintenance safety.

For vessel or vehicle owners, the key acts as a theft deterrent, preventing unauthorised use of the engine or electrical system. For technicians and DIY enthusiasts, it serves as a safety lockout, ensuring the circuit cannot be accidentally energised while working on the electrical system. This reduces the risk of short circuits and electrical shock during repairs.

Engineered for Harsh Environments

Reliability in marine environments requires superior materials. The m-Series uses tin-plated copper studs to offer maximum conductivity while resisting corrosion caused by salt mist and humidity. The studs feature a one-piece design, which is a significant improvement over standard two-piece bolts. This design ensures the stud never loosens from the switch body over time, maintaining a solid electrical connection and reducing the risk of overheating—a common point of failure in generic switches.

The unit is housed in a reinforced casing with an isolating cover that protects the rear contacts from accidental shorting. Breakout tabs on the cover allow for wire access in any direction, simplifying the wiring process in complex setups.

Versatile Connection Options

The switch is designed to accommodate modern heavy-duty cabling. The 3/8" (Approx. M10) stud terminals are robust enough to accept heavy-duty lugs, ensuring secure, low-resistance connections. With a stud length of 7/8" (22 mm), the terminals can accept multiple cable lugs, allowing for easy integration of additional loads or charging sources directly at the switch.

  • 300 Amps continuous rating handles substantial 12V, 24V, and 48V loads comfortably.
  • Lockable key design prevents accidental activation and enhances security.
  • Tin-plated copper studs ensure maximum corrosion resistance and electrical flow.
  • One-piece terminal studs prevent loosening, reducing fire risks and connection failures.
  • Flexible mounting with breakout tabs supports various cable entry angles.
  • Ignition protected marking makes it safe for installation aboard petrol-powered boats.

Improve System Safety Today

Upgrade your battery management system with the Blue Sea m-Series Lockable Switch. Whether you need to secure a vehicle against theft or ensure safe isolation for maintenance, this switch delivers professional-grade performance in a compact package.

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 47674048636

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Jose Correa
Port Orchard, US
★★★★★ 5
Stunning Automatic Watch With TopTier Durability and Precision
Color: Grey
“I got this Tissot PRX for my cousin’s birthday and bro fell in LOVE instantly. This thing keeps time like a beast, never slows down, never lags. Automatic movement, so no batteries, no drama. Durability? Stupid good. You can hit it, bump it, live life rough, it still looks box fresh. Size wise it was almost perfect. I just had to remove two links, nothing big. It’s light, functional, comfortable, doesn’t weigh you down, doesn’t get in the way but more importantly I can say this watch is in everyone’s eyesight when we wear it. Cause of course I had to get another one! Basically. I gave him a very nice piece as a gift, and now he’s walking around like he owns Switzerland.
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Reviewed in the United States on December 11, 2025
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Verified Purchase
Cienfuegos
Chelsea, US
★★★★★ 5
Great watch!!!!
Color: Grey
Excellent quality, one of the best, elegant.
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Reviewed in the United States on May 6, 2026
T
Verified Purchase
T. H.
Port Orchard, US
★★★★★ 5
Excellent value for an automatic watch, keeps VERY good time.
Color: Grey, Color: Grey
I've only had the watch for a day but wanted to leave a quick review on it to share a couple of notes. So far it keeps VERY good time, better than any of the automatics I own (including a Rolex Submariner, Tag Heuer Aquaracer, Tag Heuer Formula One, and several other sub $1k watches). I set it to an atomic time app on my phone yesterday and 24 hours later it's still SPOT on - hasn't gained/lost even a 1/10 of a second. I was shocked to see it's kept PERFECT time for the last day, I'm really blown away so far. I've worn it the entire time, we'll see how well it keeps time while being stored in a winder. This picture shown is the watch with a 22mm leather band on it, fit's without any issues (just need to squeeze in the leather a tad). I doubt it would work with a 22mm metal bracelet, but leather works great. Just FYI since the 21mm lug width is kind of odd. The face isn't quite a lustrious as the images make it look, but it's still a great-looking watch. For a sub $1000 automatic you can't go wrong, this is a fantastic watch at a great price. It'll be my daily driver for some time I'm sure. If I have any issues in the future I'll update the review.
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Reviewed in the United States on March 22, 2021
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Verified Purchase
Beniamin Grigoryan
Birmingham, US
★★★★★ 5
It looks really cool and striking.
Color: Grey, Color: Grey
Really cool and beautiful watch. Although my specific unit runs 5 seconds fast every day—at first it’s annoying, but eventually you stop caring. 🤣
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Reviewed in the United States on April 16, 2026
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Verified Purchase
Paul Andreini
Battle Creek, US
★★★★★ 5
A Beautiful Timepiece at an Awesome Price!!
Color: Grey, Color: Grey
I have lusted after this watch for four months. I first tried on a similar model (stainless steel band with a green face) in a local jewelry shop (Spitz Jewlers, Walnut Creek, CA, USA). It was "love at first sight," even if I didn't love the white lines on the face from 12-6 and 3-9. At the time, the MSRP was $775. The MSRP has since increased to $795. But I bought this beauty on Amazon.com for only $524.99; after applying the cash-back from my Prime credit card, this watch costs only $498.75. This was "the offer that I could not refuse," to quote from "The Godfather." Accuracy could be better: after only a few days, it is now 7 seconds behind my phone (to which I set my new watch). But I don't really care about that all that much. This is why I rated "accuracy" at 4 stars, but my overall review is 5 stars. My video shows the date changing suddenly at 11:59:59pm, just how I want it; in another photo, you can see that my Seiko changes the date more slowly, which I do not like. This watch is absolutely phenomenally beautiful. If you're on the fence over whether to make this purchase, then I would say "go for it!" You will not find a prettier, more accurate watch at a lower price in ANY store in the entire USA.
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Reviewed in the United States on April 28, 2023

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