HomeDeco Hardware Black Double Wheels Horseshoe Sliding Wood Barn Door Hardware Flat Tracks System for Single Door (8FT Single Door Kit) Surface: black frosted, high quality carbon steel, corrosion protection, environmental protection, non-pollution Track and roller arm thickness: 0.23 inches. Screws: 8.8 grade high strengh bearing capacity. Stopper: rubber covered, good buffer effect, reduce the noise Roller bearing: High purity bearing steel Gcr15, passed the test of opening - closing for 100000 times, wear-resisting, ensure the stability of the move and the wheel's fluency We are professional factory, accept custom-made barn door hardware Service: 5 years warranty, 90 days return time (If you did not like it or no longer need, under situation of the product does not affect the second sale that you could return to us)