Grooved Roller for Sliding Windows
This Roller is constructed out of Aluminum and Nylon
The Roller is Nylon
The axle pins are Aluminum
Its surface is Center Grooved
This design is used by several manufacturers

Material: Nylon and Aluminum
Roller Diameter: 1/2 inch
Roller Edge Type: Grooved
Roller Width: 1/4 inch

Contents
4 rollers
4 axle pins

Priced and sold as a package.