1. Built-In High-Frequency Antenna, Corresponding To The Antenna Depth, Eliminates Blind Spots, And Reads The Entire Data Card Without Interruption. 2. Increase The Frequency Of Keystrokes, The Size Of The Card Can Hold Everything. The Data Analysis Is Completely Stable And The Error Rate Is Low. 3. The Low-Frequency Antenna Improves The Signal-To-Noise Ratio, The Recognition Speed Is Higher, And The Mobile Design Meets Various Needs. 4. No Antenna Interface, No Need To Connect, Easy To Damage. 5. It Is Simple And Convenient To Cancel The Lithium Battery. (In Offline Mode, You Can Use The Power Bank) Material: PC+Metal colour: black Package Contents: 4 x RFID Card Reader 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.