Prime-Line B 571 Center Grooved Spring Tension Roller Assembly, 1 in Dia Roller, 1/4 in W Roller, Steel Roller, 2 in L

This is a tension spring roller assembly with a V shaped spring design is used by several patio door manufacturers. The roller is a 1 in steel ball bearing roller with a heat-treated steel tension spring that is V shaped. The 2 in L V shaped flat spring inserts into the screen frame giving tension required as the door slides back and forth.