My dog previously had a standard velcro harness that didn't adjust to fit my dog's body shape. As a Westie, he has a slightly broader chest and strong upper legs than other small to medium-sized dogs. The velcro harness I was using previously was just not something he enjoyed putting on because it rubbed on his chest and legs too much while he was walking.
The Summit harness (and all their harnesses) have three click-in spots, which can all be adjusted. Adjusting everything to fit my pup the first time did take some time, but now that we have it set up he is so comfy and happy. It's sturdy and I love the handle on top of the harness to more comfortable keep a hold on him around other dogs or in uncertain circumstances. I highly recommend.