Working Concepts EXTREME Standing Mat (14" x 21" x 1") 14 x 21 Black 14" x 21" x 1"1" thick closed cell nitrile foam rubber Designed for fixed workstationsWill, not compression set Keeps body in gentle motion to improve circulation and joint lubricationSelf extinguishing Eliminates high-frequency vibrationsWill not absorb liquids Yellow safety caution bars alert 1" heightSilicone free