General Purpose Mechanical watch from Marathon featuring a new dual winding movement, scratch resistant sapphire crystal, and an improved water resistance. Designed to be used in the field by infantry or other military personnel and built to the strict military standards of MIL-PRF-46374G, the GPM is just as at home being worn by a civilian as it is in uniform. The GPM is a true all purpose watch that will be your reliable companion for years. The new GPM with Composite Case uses a Japanese made “Dual Winding Movement” (DWM) and can be wound both by manually winding the crown or by use of the automatic self-winding rotor (transferred energy caused by the movement of the wrist). With our new watch winding system, the user will notice that there is a mechanical noise and the rotor can be felt oscillating; reassuring the user that the automatic winding system is performing as intended. Once fully wound the GPM will run for approximately 41 hours without the need to be wound again, or can be worn to wind using the automatic self-winding rotor.