This Dinosaur Dog Harness is too cute to not have for your best friend who happens to love dinosaurs as you do! The neck and chest are resizable straps. It's reversible and has a geometric design on the other side. It measures approximately the following: the XS (Chihuahua) is 10"-15.5" for the neck and 13.5"-18.5" for the chest; the S (Dachshund) is 14"-18.9" for the neck and 16"-21.3" for the chest; the M (Beagle) is 17"-20" for the neck and 18"-24.4" for the chest; the L (Australian Shepherd) is 18.5"-22.4" for the neck and 22.4"-32.7" for the chest; and the XL (Golden/Labrador Retriever) is 19.7"-24.8" for the neck and 23.6"-35" for the chest.