Leather is 100% genuine cowhide leather. Width is slightly under 1" or 24 mm. Basic 1.75" round buckle plated in old brass finish.  

S/M: Start of leather to 1st hole: 30", to middle hole: 32", to last hole: 34" to end: 38" M/L: Start of leather to 1st hole: 34", to middle hole: 36", to last hole: 38" to end: 42" L/X: Start of leather to 1st hole: 38", to middle hole: 40", to last hole: 42" to end: 46"