Prime Line Products B576 Sliding Screen Door Roller AssemblyPrime Line Products B576 Sliding Screen Door Roller Assembly Features:; Steel ball bearing wheel with center groove; 2-1/4" flat, heat treated, high tension spring; Bent spring design used by Metal Industries and Academy Mfg. Co; Contains two rollers and two No. 8 x 3/8" Phillips sheet metal screws; Carded