Are you having trouble sliding your screen door open or closed? Have you checked your rollers/roller assemblies? Don’t replace the entire door. For a fraction of the cost of a new door, replace those worn-out rollers. This high tension steel spring roller assembly fits onto the Columbia Uni-Fit series door. This roller assembly has a 1 Inch diameter steel ball bearing roller mounted in the housing. The flat steel spring end catches onto the inside of the door frame while the flat edges of the two tabs extending out in front of the roller restrict the roller from retracting too far up into the door frame as it rolls. This sliding screen door roller assembly insert has a thinner high density polyethylene frame than the Prime-Line part B 646. It has an adjustable high density polyethylene inner housing and high density polyethylene roller. The assembly inserts into the bottom or top of the sliding screen door using the included screws. The roller adjusts to the correct position needed. This style is found on Columbia sliding screen doors but is also used on a variety of other sliding screen door manufacturers. Please note dimensions and design when comparing with old roller. Order yours today and have your door slide like new.