A detachable crank key used for opening lock paddles with two socket sizes for use on different lock designs.
These galvanised coated lock keys have been manufactured with the two most common lock windlass socket sizes within the British Waterways.
The 'L' shape design provides enough leverage to wind the lock paddle up or down. The handle has a freely-rotating sleeve which helps prevent blisters caused by the friction of turning metal on the skin. The handle is also long enough for two hands to hold and apply pressure to wind the paddles.
The overall length of the lock windlass is a happy medium, long enough to reduce effort of turning yet short enough not to get in the way.
Lock 'windlass' can also be known as 'lock keys', 'iron', 'lock handle' or simply 'key'.