Easy to carry;Water resistant;Can read and rewrite Each comes with key fob included Compatible with 125khz RFID reader to access No external power required. It applies to access control, hotel locks, staff attendance and access control school campus and payment control, identification and security , parking entry and payment, social security management, transportation payment, , municipal and ancillary service payment T5577 chip which compatible with EM4305 chip Weight: 47g (10 pcs) Operation frequency: 125 kHz Read and rewrite key tags Detection distance: 0-5 cm colour: random color, ' accept the specified color Material: Plastic size: 3.5x2.9x0.5cm Package Contents: 50 * T5577 Keytags Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.