This tag is designed for 8.2MHz RF systems. The tag measures is 2.13″ (54mm) in diameter and comes in Black. Middle Dome Tag combines great detection capability with a visually appealing design. It looks elegant and modern while at the same time being one of the hardest tags for would-be thieves to try to defeat. The clamshell type design means there is no opening to try to cut the tag off or to even pry open. We highly recommend this tag.