PN 439013: Taking a standard 10' clamp and adding Speed Rail fittings makes this clamp one of the most versatile clamps, adjusting from 10' to 20'. Riding on standard 1-1/4' Speed Rail this multi-purpose clamp can make any rigging challenge easier. Matthews C Clamps are manufactured from premium drop forged steel. It should be noted however, that since the Matthews clamp is an adaptation of a standard C Clamp, there is no effective warranty on the part. Black only.