Compression socks

A sock with a number attached to it.

A compression sock applies measured pressure, strongest at the ankle and decreasing up the calf. That gradient is the product. It is stated in millimetres of mercury and it is the one property a buyer can test independently.

This makes compression different from every other construction in the catalogue. Elsewhere the specification describes how the sock is made; here it describes how the sock must perform, and the knitting is whatever achieves it.

The pressure class. State the mmHg range at the ankle. Everything else in the construction, including the yarn and the machine, follows from that number.

Which standard, if any. Different markets recognise different compression standards and different testing regimes. Tell us the destination market before sampling, not after.

Sizing by measurement. Compression socks are graded on ankle and calf circumference. A sock sized on shoe size delivers the wrong pressure on most wearers, which defeats the purpose of buying one.

Open or closed toe. Open-toe is standard in clinical supply and rare in retail. Decide early: it is a different foot pattern, not a modification.