EID Tag Comparison - CattleTags.com
Global 982 vs USDA 840 - What's the difference?
Using USDA EID tags (which start with 840) is the best option because they are considered Official ID in all US states and are approved for interstate travel. With USDA tags, a Premise ID is required which can be applied for through your state's animal health department.
Half Duplex vs Full Duplex - What's the difference?
Half Duplex (HDX) tags are better able to transmit through metal interference such as metal and steel objects. Full Duplex (FDX) is good when read range is not an issue.
Typical read range on HDX tags ranges from 38cm - 46cm (15" - 18") while typical read range on FDX tags ranges from 35cm - 41cm (13" - 16"). However, FDX tags are more susceptible to interference from metal and steel objects such as headgates, panels, and squeeze chutes as well as fluorescent lights.