ACME made clickers for WW2 - famous at the D Day landings as used to determine whether a person was 'friend or foe'.
Made in metal we have managed to get the factory to make these clickers for the animal market.
Most clickers are plastic and OK for occasional use.
The ACME model is rugger as used by the Army.
Ideal for training dogs, horses and other animals including marine mammals.

You could always brush up ,on your morse code!