Second belly strap is super close to his *. All areas of contact are adjustable. Second strap lands geographically across my boys.
Small won't fit a jack russel. The back strap is inconvenient.
Length is good and it has plenty of patch room. The d-rings are very big so i can't attach any tags to them but they work fine with his leash so i'm not worried.
My little boy is too strong for this. Does not stay in place.