This set of 20 monofilaments (or Von Frey Hairs) is based on the Semmes Weinstein monofilament set, but now features retractable filaments to protect the filament and allow the investigator to carry a few around in a pocket.
The Semmes Weinstein set of monofilaments provide an approximately logarithmic scale of actual force, and a linear scale of perceived intensity. They have a long history of effective use in clinical settings, and can be used to diagnose pathologies of hyper- or hypo-aesthesia. Subsets within the set of 20 probes distinguish pathologies on different parts of the body (foot, hand, lip, cheek, etc.).