Hi Curtis – Salu has a Julius harness and wears a “0” as well with a little room to spare. He’s 45 lbs but heavy boned and muscular. It’s a great hardness – he wears it for parkour.
We also have a Wonder Walker size Medium that is nice and light. Lola wears Wonder Walker size small – she’s 29-30 lbs and the straps are a small and it will go.