The RFID working function is affected by metal condition, so it is different from the normal RFID Tags. GYRFID presents different on metal tags.
MEA: Made of ABS material + epoxy filling
MEB - PCB Tag, Various size, designed for UHF, distance from 0.5-10m.
MEC - Ceramic Tag, Various size, designed for UHF, distance from 0.5-10m.
Other models like DIP, STE, LAP, TKA can also be with anti-metal layer for on metal application.