Features: 1) Competitive price, 2) Good quality, 3) Prompt delivery. Features: 1) Competitive price,2) Good quality ,3) Prompt delivery,4) Diameter and pitch. a) 6mm, 4:1b) 8mm, 4:1c) 10mm, 4:1d) 12mm, 4:1e) 14mm, 4:1f) 16mm, 4:1g) 18mm, 4:1h) 20mm, 4:1i) 22mm, 4:1j) 24mm, 4:1 k) 26mm 4:1 l )28mm 4:1M) 30mm 4:1