Three diameters: 75mm, 100mm, 125mm.Lightweight frame made from high density aluminium. Made from durable rubber.Handy release lever for quick release.Can also be used to assist in glass panel installation by preventing the glass dropping down the channel.All panel cups available separately, please see Power-TEC Part Nos. 91173 (75mm diameter), 91174 (100mm diameter), 91175 (125mm diameter).