Small garmin. Don't remember the name. But I use it with the Marines. We call it a dagger.
The DAGRs ("dagger") came out after my time. Been told the DAGRs are super-awesome...hell of alot better than the Pluggers (PLGR) of my latter days in service. Though I'll bet a coke and a candy bar that a DAGR (like the PLGRs) is illegal as hell for civies to possess (secure code enabled).
I've loved using an entry level Garmen eTrex without any maps, bells or whistles. Reason is that it has more than double the battery life of other more advanced Garmins. (just have to use your brain a bit more)
Down side of civilian GPS is that pine trees are the worst enemy (not much an issue with military GPS). The size of a civilian GPS signal pulse is about the same as the diameter of a pine needle and gets filtered in a pine canopy. It still works, just not nearly as well as the mil equipment.