Blue Sea Systems M-Series Battery Switch Spare Locking Key, Red

Overview

The Blue Sea Systems 7903 is a red spare locking key for compatible M-Series battery switches. It is the replacement key itself, not the switch assembly, so it is used when the original key is lost, damaged, or kept as a backup on board.

This part fits the keyed version of the Blue Sea Systems M-Series battery switch range, including the 6004 Single Circuit ON-OFF with locking key. It gives you back normal access to the switch without replacing the full battery switch body, which matters when the rest of the switch is still in good working order.

On a boat, a missing battery switch key can stop you from isolating a battery bank before storage, service, or electrical work. Keeping a spare like this aboard is a simple way to avoid that problem, especially on small powerboats, tenders, and sailboats using a keyed M-Series switch at the battery compartment or main DC disconnect point.

Key features

• Spare locking key for Blue Sea Systems M-Series battery switches that use a keyed handle
• Compatible with the keyed M-Series setup, including the 6004 Single Circuit ON-OFF battery switch
• Red key matches the red keyed M-Series switch version for straightforward identification
• Useful as a direct replacement for a lost key or as a backup kept on board
• Key-only service part for restoring access without replacing the complete battery switch

Compatibility and fit

This key is for the locking-key version of the M-Series switch, not the standard knob version and not a complete replacement lock set. Before ordering, check that your existing switch is a keyed M-Series model and that you need the spare key rather than the full switch or another service part.

Because this is a mechanical replacement key, it does not change the switch's electrical ratings or the way the battery switch is wired into the boat. Its job is simply to restore operation of a compatible keyed switch that is already installed.

Use on board

This is a sensible spare for owners who lock out battery power when leaving the boat, winterizing, or working on the DC system. It also suits technicians and service crews who want a replacement key on hand so a missing original key does not delay routine electrical work.

Shipping
We ship worldwide from the United States. Rates are calculated at checkout based on destination and package weight. Some items include free shipping, which will show automatically. Not every product is eligible for international shipping; checkout will confirm eligibility. We do not ship to PO Boxes except through USPS, and not all packages qualify.

Processing and dispatch
Most orders are verified, packed, and handed to the carrier within 1 to 2 business days. Some products may need extra handling time or ship directly from the manufacturer. For certain international orders, inventory transfers between warehouses may add time. If any delay is expected, we will let you know the dispatch date.

Delivery and tracking
Deliveries are handled by trusted carriers such as USPS, UPS, FedEx, and DHL. Estimated arrival times appear at checkout and depend on your location and the service you choose. These are estimates and can be affected by customs or carrier disruptions. A shipping confirmation with a tracking link is emailed when your order ships, and tracking may take up to 24 hours to update. You can also view tracking in your account.

Duties, taxes, and support
International customers are responsible for any customs duties, taxes, and fees charged by the destination country. If these charges are refused and a shipment returns to us, the carrier’s return cost and any re-entry customs fees will be deducted from the refund. If your order is late or you need help, contact cs@qualityboatparts.com and we will assist you.

Quality Boat Parts is a reseller. Many items include a manufacturer’s warranty, and all warranty service is handled directly by the manufacturer. We do not manage or administer warranty claims on behalf of customers.

Warranty terms, coverage, and duration are set by each manufacturer. Issues involving defects, repairs, or replacements must be addressed with the manufacturer’s support team. When available, the warranty period is listed on the product page. If it is not shown, contact us or the manufacturer for details before purchasing.

To start a claim, the customer must contact the manufacturer and follow their process. Keep your proof of purchase and original packaging, and register the product if the manufacturer requires it, as these are often needed for warranty service.

We are happy to help you find the right contact or documentation, but we cannot decide outcomes or intervene in claim resolutions. For guidance, email cs@qualityboatparts.com.