Making your own sub-woofer/speaker? then you will need professional looking speaker connections to finish the job off. High quality with solder connections on back of each binding post. GOLD PLATED FOR BEST QUALITY! Dimensions are as follows: Outer circle diameter - 68mm/2.7"" Total diameter - 79mm/3.1"" (square) Depth - 25mm/1"" Use a 2 3/4"" diameter drill to cut the correct size hole.