Waterproof ABS RFID key tags built with durable shockproof construction for long-lasting access control use. TK4100 chip operates at 125kHz frequency with unique pre-programmed IDs printed on each card for security verification. Portable key ring design (3.3x2.9x0.6cm) enables easy attachment to keychains and backpacks with teardrop shape for ergonomic handling. Compatible with standard ID access systems including door entry devices, parking gates, and attendance tracking equipment. Ideal for commercial or residential security applications: office buildings, school campuses, hotel locks, and employee management systems. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.