The iButton is a key-sized device that contains a computer chip and attaches to a keychain. Each chip has its own unique ID number and is unaffected by magnetic fields, metal detectors, water and most common chemicals. In other words, no two iButtons are alike. The iButton is a rugged, hermetically sealed, weatherproof identification device contained in a stainless steel can, measuring 16MM in diameter and 5mm thick. You can drop it, step on it, scratch it or wear it swimming. The iButton is wear-tested for 10-year durability and can be reassigned to a new user quickly and securely. The iButton will only work with the iButton Solo Keyless Lock. You can also use the same iButton on multiple locks once programmed. Hands-On Research: When testing this product I was amazed at its perfect design. I found the iButton to be incredibly durable and reliable. I probably tested the iButton about 500 times, and amazingly enough, it didn't fail one time. The iButton Solo Keyless Lock recognized the iButton within 1 second of the keyfob's proximity to the sensor. What's Included # 5 iButtons with attached keyfob # Instructions