These stainless steel mounts were specifically designed to mount antennas on the flat side-view mirror arm supports commonly found on pick-ups. When used in this manner, there is no need to drill any holes in the vehicle or mirror support arm. Of course, this mount can be used in other applications as well. The upper bracket is 4.6" (117mm) long by 1" (25mm) wide. The distance between the stainless steel clamping bolts (supplied) allows the mount to span material up to 1.4" (36mm) wide. If the lower clamp is omitted, the upper bracket will also serve as a flat mount for installations with a horizontal surface to bolt it to. Each mount also comes with a Firestik K4A mounting stud with a screw on coax connection. For general use, we recommend that these brackets be used with antennas up to 4' (1.2m) in length.