While I am on the topic, the best product I have seen in a long time is the DuraSafe Universal Electronics Lock (UEL-50).
This is a gimbal knob lock that replaces the factory gimbal knob on most chartplotters and fishfinders from leading manufacturers including Humminbird, Lowrance, Garmin, Eagle to name a few. The UEL-50 also fits most Marine Radios from leading manufacturers like Standard Horizon and Icom and most other devices which use a common U-Bracket/Gimbal knob set up.
The UEL-50 Gimbal lock is an excellent and inexpensive insurance policy to keep your electronics safe and deter simple theft of your expensive electronics.
At $25 each, the UEL-50 comes complete with locking mechanism and adapters to fit almost every product on the market. If you have several units on your boat, we can supply locks with common keys upon request!
I also give a personal endorsement for this product. I use them on my boat and on every display unit in the showroom and show displays!