Rolled Round SOFT Leather Dog Martingale Collar Soft Padded Size XSmall to XLarge Breeds (Black, Size S1 refer. number 7528) *Size XS1 Width 1/4''. Ref 7526. Inner circumference: tightest 6", widest 9"* *Size XS2 . Width 1/4''. Ref 7527. Inner circumference: tightest 7 4/5", widest 10 2/3".* *Size S1 Width 5/16''. Ref 7528. Inner circumference: tightest 9 1/2", widest 14 1/2".* *Size S2 Width 5/16''. Ref 7529. Inner circumference: tightest 11 4/5", widest 15 1/3".* *Size M1 Width 3/8''. Ref 7530. Inner circumference: tightest 13 1/3", widest 16 1/2".* *Size M2 Width 3/8''. Ref 7531. Inner circumference: tightest 15 1/3", widest 19 1/3".* *Size L1 Width 1/2''. Ref 7532. Inner circumference: tightest 17 1/3", widest 22".* *Size L2 Width 1/2''. Ref 7533. Inner circumference: tightest 19 1/3", widest 23 1/5".* *Size XL1 Width 3/5''. Ref 7534. Inner circumference: tightest 21 1/4", widest 25 1/5".* *Size XL2 Width 3/5''. Ref 7535. Inner circumference: tightest 23 2/3", widest 28".*