The difference is to adjust to the difference in wheel thicknesses. The US-105 is designed for the 50mm thickness of the SG-250 and other 250mm diameter wheels. The US-103 is specifically designed for the 40mm thickness of the SG-200 and other T4 wheels. Many years ago, we had a forum post by a member whose chisel was falling off the edge of his support bar. He was using the shorter US-103 with the thicker SG-250 wheel.
I agree with TGB about the onger US-430 support bar. It is a must for knives longer than eight inches.
Ken
I agree with TGB about the onger US-430 support bar. It is a must for knives longer than eight inches.
Ken