Feature: 1. Induction Design: High sensitivity, high frequency, fast reading speed, induction distance is within 10 cm, which is related to the card reader. 2. Outstanding Features: Innovative technology carefully crafted, fine workmanship, wear resistant and waterproof, drop proof and not easy to break. 3. Excellent Advantages: This door lock key fobs is compact, lightweight, easy to carry and store, and simple to use. 4. Application: Smart cards provide an alternative way for seniors or children to enter the home without the need for a smartphone or keys. 5. Stable Performance: This access card is made of ABS and iron and silicon and copper materials, stable and reliable performance, durable and long service life. Specification: Item Type: Door Lock Key FobsMaterial: ABS and iron and silicon and copperProduct Size: Single 3.5x2.8cm/1.37x1.1in .Built in Smart Chip: Model: TK4100 Frequency: 125 KHZ Package List: 1 x Package of Door Lock Key Fob(100PCS） Note: 1. Please allow slight error due to manual measurement. Thanks for your understanding.2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.