Card-Tech 5pcs CT-WP015 125KHz LF TK4100 silicone rfid wristband RFID waterproof wristrfid used in Concert tickets SPA member management This is EM4100/4102 ,is Read-only, not programable,not HID! Writing distance with reader:1-5cM (LF) Bright colors, eye-catching, environmental safety Waterproof, good against heat ,shock ,moi Application Widely used for Concert tickets ,SPA member management,Sport management, Swiming pool management ,etc., It can track their position by using RFID.