This professional combination screen rolling tool is constructed of plastic concave and convex rollers with steel ball bearings and a wooden handle. It is used to install screen mesh materials and vinyl spline into window and door screen frames. This tool can be used to install spline ranging from .115 to .165 in diameter. The convex wheel is 1/16" thick and has a 2-1/2" outside diameter. The concave wheel is 3/32" thick and measures 2" in outside diameter.