To size the IPS Back Pad by Pro-Tec, take the measurement from the nape of the neck to the bottom of the back. Approx Measurements;
Small = 40.7cm - 45.7cm (16”-18”)
Medium = 45.7cm - 50.8cm (18”-20”)
Large = 50.8cm - 55.9cm(20”-22”)
X-Large = 55.9cm - 61cm (22”-24”)
Sizes of products may vary between manufacturers and even between different designs by the same manufacturer. The size charts should be used as a general guide.