ZEKOO Rustic 5-16 FT Bypass Barn Door Hardware Powder Tcbunny Sliding Steel Track for Double Wooden Doors (10FT Bypass System)Main Material & SurfaceBlack frosted, high quality carbon steel, corrosion protection, environmental protection, non pollution. DesignTrack and roller arm thickness: 0. 23 inches, very sturdy. Screws: 8. 8 grade high strengh bearing capacity. Stopper: rubber covered, good buffer effect, reduce the noise. Roller bearingHigh purity bearing steel Gcr15, passed the test of opening closing for 100000 times, wear resisting, ensure the stability of the move