Double ribbed edge for a better fit. Ankle support fabric. Inner cuff from tip to calf. Cumplen according to IEC 61340-5-1:2007, Ed. 1.0 meets the following requirement: R<3.5 x 107Ω. According to test report from 3.06.2008: vertical resistance. Mean 1.2 x 104Ω *STFI (Sächsisches Textil Forschungs Institut e.V) - Evaluation of electrostatic behaviour: (test report no. 1062/08 from 03.06.2008)