This T-shirt/Tank has a built in, strong and secure, Nylon D-ring Harness, with a quick release buckle. Made from high quality 100% cotton.
For sizing, you may find the following a helpful guide for a quick assessment.

Size	Weight
XXS	1-2 lbs
XS	2-5 lbs
Small	6-10 lbs
Medium	11-15 lbs
Large	16-32 lbs
X-Large	33-45 lbs
XX-Large	46-70 lbs
XXX-Large	71-100 lbs