A control module for regulating the operation of a power generating unit of a powered surgical tool, said control module including: a shell formed from at least one panel (51, 52, 53, 54 and 63) that is shaped to define a void space, wherein said shell is designed to shield the void space from the outside environment and the at least one panel is shaped to have at least one opening; components disposed in said shell void space for regulating operation of the tool power generating unit; at least one conductive pin that extends through the at least one opening in the shell panel for providing electrical communication between the components internal to the shell void space and at least one of the tool power generating unit or a power supply of the powered surgical tool; and a seal unit disposed in the opening of the at least one panel, the seal unit extending between the pin and an inner wall of the panel that defines the opening; characterized in that the seal unit consists of: an outer stop disposed in the panel opening around the pin, said outer stop extending to the inner wall of the panel that defines the opening; an inner stop disposed in the panel opening around the pin, said inner stop extending to the inner wall of the panel that defines the opening, the inner stop being spaced away from said outer stop; and an active seal (79, 127) disposed in the panel opening around the pin and that is located between the outer and inner stops (76, 77), said active seal including: a boot, said boot shaped to have: an inner skirt that extends circumferentially around the pin adjacent the opening-defining inner wall of said panel; an outer skirt disposed around the pin adjacent the inner wall of the panel; and a base that extends between said skirts; and at least one biasing member that is located between said skirts and that biases said outer skirt against the panel inner wall or said inner skirt against the pin. a shell formed from at least one panel (51, 52, 53, 54 and 63) that is shaped to define a void space, wherein said shell is designed to shield the void space from the outside environment and the at least one panel is shaped to have at least one opening; components disposed in said shell void space for regulating operation of the tool power generating unit; at least one conductive pin that extends through the at least one opening in the shell panel for providing electrical communication between the components internal to the shell void space and at least one of the tool power generating unit or a power supply of the powered surgical tool; and a seal unit disposed in the opening of the at least one panel, the seal unit extending between the pin and an inner wall of the panel that defines the opening; characterized in that the seal unit consists of: an outer stop disposed in the panel opening around the pin, said outer stop extending to the inner wall of the panel that defines the opening; an inner stop disposed in the panel opening around the pin, said inner stop extending to the inner wall of the panel that defines the opening, the inner stop being spaced away from said outer stop; and an active seal (79, 127) disposed in the panel opening around the pin and that is located between the outer and inner stops (76, 77), said active seal including: a boot, said boot shaped to have: an inner skirt that extends circumferentially around the pin adjacent the opening-defining inner wall of said panel; an outer skirt disposed around the pin adjacent the inner wall of the panel; and a base that extends between said skirts; and at least one biasing member that is located between said skirts and that biases said outer skirt against the panel inner wall or said inner skirt against the pin. an outer stop disposed in the panel opening around the pin, said outer stop extending to the inner wall of the panel that defines the opening; an inner stop disposed in the panel opening around the pin, said inner stop extending to the inner wall of the panel that defines the opening, the inner stop being spaced away from said outer stop; and an active seal (79, 127) disposed in the panel opening around the pin and that is located between the outer and inner stops (76, 77), said active seal including: a boot, said boot shaped to have: an inner skirt that extends circumferentially around the pin adjacent the opening-defining inner wall of said panel; an outer skirt disposed around the pin adjacent the inner wall of the panel; and a base that extends between said skirts; and at least one biasing member that is located between said skirts and that biases said outer skirt against the panel inner wall or said inner skirt against the pin.