Bennett Marine's Hydraulic Power Unit creates hydraulic pressure in order to lower and raise trim tabs. Its purpose is to direct fluid flow to the actuators. Bennett Marine's H1179 Mounting Brackets are sold separately from the Hydraulic Power Unit. For installation and mounting purposes, the Hydraulic Power Unit measures out to be 4" x 7-1/2" x 5-1/2". Refer to manufacturer recommendations and installation guidelines to ensure a proper fit for your application.