The EZ4090 EZProximity Proximity Round Stickers are made of PVC and an adhesive backing. These proximity tags are perfect for applying onto your existing non-technology ID card or on the back of a phone or watch. Like every credential on the market, the read range is dictated by the antenna size. And since these tags are much smaller than a full card or key fob, you can expect a shorter read range than our EZProximity cards and key fobs. Comparable to HID Part Number: 1391 MicroProx Tag. Dimensions: Diameter: 1.278 in (32.5 mm)