Specification: Diameter from M20, M22, M24, M27, M30 or 3/8" to 1-1/8", length from 20mm to 600mm, or 1-1/2" to 26". T bolt for concrete sleeper 1. Standard: TB, AREA or ASTM, BS, SS and UIC or other standard or drawing required by clients. 2. Specification: Diameter from M20, M22, M24, M27, M30 or 3/8" to 1-1/8", length from 20mm to 600mm, or 1-1/2" to 26". 3. Grade: 4.6, 4.8, 5.6, 8.8, 10.9, ...