1. Using 6-layer board technology, low-frequency coil has high Q value, high sensitivity, and long luminous distance. 2. High frequency uses diode voltage doubler circuit, which has high sensitivity and long luminous distance. 3. Low frequency and high frequency are placed in a staggered manner, and they do not weaken each other in the smallest volume, ensuring the best performance in a small size. 4. Using epoxy resin drip glue technology, it is waterproof and moisture-proof, wear-resistant and drop-resistant, and can be carried with you This is an ultra-sensitive field strength detection card that integrates high frequency and low frequency. It can be used to detect the card reading frequency and signal strength of the access control reader. It is an indispensable tool for lock matching, access control installation, and RFID debugging. The RFID Field Detector detects and displays the presence of Low Frequency (125KHz) and High Frequency (13.56MHz) fields. Designed to be compact and discrete, it fits neatly onto your keyring. The RFID Field Detector is an indispensable tool. When in the presence of an RFID field, an LED indicates the frequency of the field. Specifications: 13.56Mhz (high frequency IC reader): glows white light Proxmark3 RDV4.0: 70mm (farthest) ACR-122U: 68mm (farthest) 127Khz (low frequency ID reader) glows red light Proxmark3 RDV4.0: 65mm (farthest) Wall reading head: 30mm-50mm Colour:Black & Gold Material:plastic Due to different batches, there may be differences in product appearance and printed text, which will not affect use Package Contents: 1 * RFID Field Detector Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.