The Pinlock system is based on three basic principles, which together work like nothing else. First, unlike the visor, the Pinlock insert lens is made of a soft and porous moisture absorbing material. The thicker materials of these lenses absorb more moisture and offer more impact protection. Second, the airtight pocket between the Pinlock insert and the visor creates an extra insulation layer, further increasing the anti-fogging properties of the total system. Fogging up is a thing of the past. Pinlocks are easy to fit and quickly change between tints, etc., or keep it clear. The choice is yours! Cheaper than replacing your visor! This Pinlock insert fits the Frank Thomas FT39 motorcycle helmet.