Every walk kit pairs one leash style with either a collar or a harness, in matching colors, at a 10% saving versus buying the pieces separately. The choice between a collar and leash set or a harness and leash set comes down to where the leash pressure sits during the walk, not to material or build quality: both kit types use the same Italian vegetable-tanned leather and solid brass hardware.
Some owners buy both kit types and rotate them, a collar and leash set for short errands, a harness and leash set for longer walks. Sizes run XXS to XL on collars and XXXS to XL on the harness, so both kit types cover small breeds through large and giant breeds.