These sliding door rollers are constructed in steel, and come in a zinc-plated finish. Each roller features a 105 lb. maximum load capacity rating and concave (grooved) edges for use on raised tracks found in patio sliding doors, sliding screen doors and sliding wardrobe and closet door systems. These 1-1/2 in. outside diameter rollers are constructed with steel center races, 1/4 in. inside diameter axle holes and they are only 5/16 in. thick. Rollers like these are used in several patio and closet door roller assemblies. Use these rollers to replace damaged wheels, missing wheels and plastic wheels as needed.