Material: cotton Size Cervical Wearing Length Waist Small 16cm / 6.3 "-22cm / 8.66" 13cm / 5.12 "25cm / 9.84" -31cm / 12.2 " Large 19CM / 7.48 "-30CM / 11.81" 19CM / 7.48 "25cm / 9.84" -40cm / 15.75 " Product Features 1, flexible cloth sweat breathe, soft warm, not easy to start, very comfortable 2, there is a button to adjust the size, apply to the vast majority of guinea pigs and young rabits 3, three-dimensional cropping is suitable for cat dogs, making pets more skin-fitting Package Include: 1 x Pet chest strap Notes: 1. Please allow 1-3 cm difference due to manual measurement and 3-5 g for the difference between different colors. 2. Due to the screen difference, the color may be a little different from what you expect, please allow it. 3. 1.00cm=0.39"