Keri's NXT-C Standard Light Proximity Card provides maximum read range performance in a pacage considerably thinner than other "clamshell" proximity cards. It can be easily carried in a wallet or purse or worn on the clothing with a clip or necklace. These cards are extremely durable and convenient. They are manufactured with a vertical hanging slot punch,and they come with a lifetime warranty. Uses 96 bit encryption between the card and the reader.