This is a great summer oufit in four attractive colors for your baby. Something nice and casual for an outdoor stroll. For sizing, you may find the following a helpful guide for a quick assessment (inches refer roughly to length measurements). If in doubt, don't try the item on your pet if you would like to make a return): SIZEBACKCHESTNECK005 1/48 - 9 1/45 1/2 - 6 1/207 1/49 1/4 - 10 3/45 1/2 - 6 3/41810 1/2 -126 1/2 - 7 1/229 1/412 - 147 1/2 - 8 3/4310 3/414 - 168 3/4 - 10 1/2412 1/216 - 18 1/210 1/2 - 125 (Was Size 4.5)1418 1/2 - 20 1/212 - 13 1/26 ( Was Size 5)1620 1/2 - 23 1/413 1/4 - 15 1/4