This butt plug features three different rings. The hollow tube within the plug allows you to combine it in several ways. When the plug is inserted you can add vibrators. lubricant or whatever you like through the hole. The plug is 4 in. long and has a max width of 2.55 in. Ring widths range from 1.65 in. to 2.24 in. Hollow diameter is 0.9 in.