A control module for regulating the operation of a power generating unit of a powered surgical tool includes a shell shaped to define a void space. At least one operation regulating component is disposed in said shell void space. At least one conductive pin extends through at least one shell opening for providing electrical communication between the internal components and the tool power generating unit and/or a surgical tool power supply. A seal unit is disposed in the shell opening, the seal unit extending between the pin and an inner wall of the opening. The seal unit consists of outer and inner stops disposed in the opening around the pin. An active seal is disposed in the opening around the pin and located between the outer and inner stops. Said active seal includes a boot shaped to have inner and outer skirts extending around the pin, and a base extending between said skirts. At least one biasing member is located between said skirts and biases said outer skirt against the panel inner wall or said inner skirt against the pin.
