From thecraftcrate.com

"Our revolutionary Cup Chucks make it easier to attach your cup to the turner without hassle! The inserts are used to ensure a snug and straight fit, to avoid uneven epoxy curing/pooling. Simply insert the chuck into your tumbler, then slide onto turner arm and thats it! Goodbye foam footballs or pool noodles! "

Please note: Foam is NOT included. Any 3/8in wide foam will work. Dog Bowl Chucks are sold separately."