I received one unit, it would not work unless the pin was pulled out a few mm. The 2.5mm pin was way too long as compared to other devices and the specification. Spoke with Peltor/3M and they indicated that the length was too long as well and said I should send it back for replacement. The replacement has the same issue.
I ended up fabricating a spacer for the pin in order to get this to work with a cell phone and a walkie talkie that take a standard 2.5mm pin.
The unit works well with the spacer, but don't expect it to work without this modification.
Pros: Solid unit
Cons: Unit requires modification to operate correctly
This review was written in the old system and had content requirements that are different than reviews written today.