Billow 2 Rows Bling Rhinestone with Heart Shape Studded Charm PU Leather Pet Collar - Black 5 adjustment holes for adjustment, please compare with below size before confirm order Size XXS: 2.0*25CM, adjustable length 17-21CM Size XS: 2.0*30CM, adjustable length 21-26CM Size S: 2.0*30CM, adjustable length 27-33CM Size M: 2.0*30CM, adjustable length 32-38CM