flat head insert nut 1.High quality 2.high precision, 3.excellent reliability. material option:1.Bearing Material ... PU roller, soft tread3. low-noise operation4. High quality roller bearing 5. with a high load-bearing capacity6. suitable for countless applications: sliding ... precision bearings, rollers, pulleys2. Popular in the world: good quality, low price, on-time delivery.3. Small order accepted 4 ...