Product Feature: 1. Exhaust outlet locates over the (body), which is convenient to install muffler to decrease noise and pollution. 2. The external force required by direction-change of series of M3B, M3R and M3L is provided by external mechanism,which can be used for position test or [stroke switch] limit switch. 3. M3C, M3D, M3Y, M3PF, [...]