They look nice and suppose you might be able to find a plug to keep crap from getting in the ends but 2 bills for 20 is a bit much for me. How about a lug wrench to fit? But they would frustrate your average wheel thief although if they wanted them bad enough just break them off.
Cool. Having grown up in a machine shop many moons ago, 7075 certainly has more strength and stress resistance than 6061.
These are pricey but worth it. I hate my current lugs. I'll have to add these to my wish list.