Birkenstock ESD sandals Kay, Flower Field Mint, narrow width, 39 The Birkenstock Kay has two straps, one of which is attached to the shaft. The second strap can be folded down using the hidden rivet on the side and worn either on the shaft or as a supporting heel strap as required. This ESD version was specially developed for employees who work in the microelectronics sector or with high-frequency technology. These shoe models actively ensure a permanent gentle discharge for the wearer. The antistatic elements in the sole equalise potential electrical voltage differences between people and their working environment by permanently "earthing" their feet. The upper is made from the skin-friendly and hard-wearing synthetic material Birko-Flor. Footbed: Anatomically moulded cork-latex footbed with additional soft bedding in ESD design. Upper: Birko-Flor. Insole: Suede leather. Sole: EVA with Electro Static Discharge (ESD). Details: two straps, each with an individually adjustable metal pin buckle. Colour: Flower Field Rose. Width: Narrow. ESD protection tested in accordance with EN 61340. Warning: The ESD range is up to 34 MOhm, i.e. not insulating.