DT Universal is a multi-use harness for training dogs not to pull. When leash is attached to front D-Ring, the harness discourages pulling - pup will turn in towards the handler when trying to strain away. When leash is attached via side-mounted D-rings, it is a pulling harness - force will be evenly distributed over chest for exercise, tracking, sledding, etc. Features: handle with floating ring, hook & loop fasteners for patches, & 3x D-rings - 1x on chest strap & 1x on each side. SIZING BASED ON GIRTH AND CHEST: X Small 21" - 25" girth, up to 18" chest Small 24" - 27.5" girth, up to 22" chest Medium 27.5" - 33" girth, up to 24" chest Large 33" - 40" girth, up to 26"chest X Large 36" - 47" girth, up to 28" chest *Please Note: Chest Strap is fixed & unable to be adjusted. If a pup has a smaller chest, they may fall between sizes. It may be best to select a harness size that's better suited to their chest and then add a girth extension, if necessary. **Patches sold separately