first they are not considered a "fiber" lower..but more like a glock composite.
they are excellent and have a lifetime warrantee.
i have had three and sold in excessive of thirty.........no complaints to date.
they have two big improvements over a std lower.
one: the trigger is single stage and much nicer than a stock mil...tho it is not a match trigger.
two: the fit for the upper lower rear pin is an interference fit....there is no upper/lowwer rattle!
as has been mentioned they are certifed for 223/5.56 only
buy with confidence.....
ohh i buy direct from the factory...current prices vary..i believe srp is $149 for a complete lower with internals and a six position colapsable butt stock.
market price seen to be in the $139 range..but shotgun news article say they bought at $119.
if i get some extra cash i will buy more..
mike in co