That's probably because they have to make just about everything. Clothing, Pack's, Straps. You name it, they make it.

One useful tip - from someone who used to work with a Saddler - is to use saddlers thread for heavy duty repairs and to keep a candle stub (silicon) in your sewing kit. Cut a notch in the candle. Run the tread through the notch. Does two things: 1) waterproofs the thread & 2) lubricates it. Makes the sewing easier.