... head Bolts: Metric size from Grade4.8 to Grade 12.9, Inch size from Grade2 to Grade10.4. Size of T head ... from M6to M20 or 1/4" to 3/4". Length can be from 10mm to 500mm.5. Surafce Finish of T head ... : plain, black, zinc plated, H.D.G,etc.6. Produce according to drawing or samples 7.Packing of T head Bolts:Inner packing ...