Made with ABS plastic...not the cheap economy plastic! Just slide the notched "wedge" over the molded stem on the outside of the cage to lock it firmly in place. Comes in Purple, Black, Gray, Green, Light Blue, Dark Blue, Yellow, Orange and Cranberry.
Look for the matching Resting Mats! Visit them - https://www.allthingsbunnies.com/EZ-Plastic-Crocks-and-Feeders-p/fbs104.htm ↗