WIDELY USED: these heater holders fit for most standard aquarium heaters,can hold 1 inch diameter aquarium heater, PVC tubing or rain bar durable,have a strong adsortion on fish tank,perfect for aquarium and any glass surface. EASY TO INSTALL AND UNINSTALL:each suction cups comes with one clip,you can adjust the position and direction of your heaters,easy to install and uninstall,Prefect for aquarium accessories. Product weight:4.2 oz. colour:black material:plastic size:3.3*3.8cm The clips diameter:24mm The suction cup diameter:33mm Package Contents: 15*Aquarium suction cup clip Please Note: These clips only suit for standard heater holder,not for airline / air tube For a better connection,please soak them in water for a while before use,they will works better. If rubber sution cup get warped,you also can soak them in hot water to relax the texture. Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.