The Pet Life LED Lighting Santas Magical Hat Sweater Pet Costume features a small and lightweight inner stitched compartment pouch containing an LED On and Off switch which controls the lights on the backside. This fun Holiday costume will help your pet stand out in style and especially fun to wear in the dark. Outershell is composed of a comfortable Polyester and Cotton blend. Features belly Velcro enclosures for convenient on and off access. Features a Leash slit holder at the back-side. Available in Multiple Sizes. Sizing Guide - From Back of Neck to Tail area ("In" Inches) 8" - EXTRA SMALL 10-12" - SMALL 14-16" - MEDIUM 18-20" - LARGE