Package Content:
4 meters / 158 inch 8mm Slot Cover Flat Seal 30mm x 30mm and 1.5 inch x 1.5 inch Aluminum Extrusion Rail - Blue
It is a necessary aluminum profile parts to keep dirt out of the rails for your 3D printer
fit 3030 series aluminum extrusion profile 8mm T-slot, also for 8mm V-slot, and 1.5" x 1.5" series 8mm slot aluminum extrusion