These came to me in some surplus items following the construction of a commercial building and I do not have any personal experience with installing or using them. (2) SA-SGPDU-C2/4 738447D Four way units (1) SA-SGODU-C8 738448C Eight way unit Complete with plastic covers holding the mounting bolts. Only one plastic cover of the smaller ones is in the photo but they both have them. I suspect they go for a seriously higher price than being asked here. Estimated at five pounds packaged for shipping purposes.