This is a 9V battery clip typically used for our wireless cameras. The ID is 2.1mm, the OD is 5.5mm. Center positive.
9V Battery Snap with 12" Leads
Steel Machine Key 3/16" x 3/16", 3/4" long. These keys are economical with high strength and will fit 3/16" keyways.
100 pack of black UV resistant nylon with flexible tape section, pull tight and does not come undone. Length 8 inches.