Clips on to 1/4" thick baffle, holds 1/4" x 4" x ?" glass or acrylic and optional media tray.I needed something to clip on to the 1/4" baffles in my 20G high sump that would help reduce micro bubbles in my display tank. These clips will allow you to insert a 1/4" tick sheet of acrylic or glass that is 4" tall and any width you like as an additional baffle. The clips also provide area to insert the optional media holder placement of foam, sponge, or other filter media. Clips are designed to be placed every 6".