Model is a 23lb Shorkie wearing an X-Large Tee
Small- back length 9.87", chest girth 13.78", neck girth 9.45"
Medium- back length11.81", chest girth 15.75", neck girth 9.84"
Large- back length14.96", chest girth17.72", neck girth12.99"
XL- back length19.69", chest girth 23.62", neck girth14.96"
2X- back length 22.83", chest girth 31.50", neck girth16.93"
3X- back length 24.41", chest girth 34.65", neck girth 19.69"
if your pet is in between sizes, go up one
made of 100% lightweight cotton