Size MD 1″ will fit 22″-28″ chest, approx weight 35lb – 50lb.. Please take a girth/circumference of chest measurement. US Patent: 7,165,511 Jessica MacDonald designed and patented the Freedom No-Pull Harness and owns the registered trademark Wiggles, Wags, & Whiskers and co-owns USA Dog Shop. To purchase direct from Jessica please select Amazon seller ID “Inventor & Patent …