Overview

The Blue Sea Systems 7903200 is a spare locking key for compatible M-Series battery switches in black. It is used when the original key has been lost or damaged and you want to restore the keyed function of the switch without replacing the full switch body.

This replacement is meant for Blue Sea Systems M-Series battery switch applications, including keyed single-circuit ON-OFF models in the same family. For boats that use a keyed battery disconnect to control access during storage, service, or layup, this small part can save replacing hardware that is otherwise still working.

Key features

• Spare locking key for Blue Sea Systems M-Series battery switches
• Black finish that matches black keyed M-Series switch configurations
• Useful as a direct replacement when the original locking key is missing or damaged
• Lets you keep the existing switch in service when only the key needs to be replaced

Compatibility and fit

This part is for M-Series battery switch setups that use the locking-key style. It is a good match when the switch itself is still in place and functioning, but the keyed insert has been lost, broken, or needs to be kept as a spare on board.

Before ordering, match the switch family and keyed style already installed on the boat. That matters most on refits and service work where Blue Sea Systems battery switches may be mounted near the battery bank, inside a locker, or behind a panel and different switch series can look similar at a glance.

Use on board

This replacement makes sense for owners, yards, and service techs who keep spare electrical parts on hand for routine maintenance. It is especially useful on boats where the battery switch is part of the normal shutdown routine and the keyed function still needs to be available after the original key goes missing.