they are great, especially when NIW ones are the cost of 70% USGI used mags.
The bad thermolds were canadian manufactured with a different plastic mixture. The rumor was that they Ther-melted under full auto fire.
In my Brush-hampster they are a tad tight & don't drop free.
Not much of an issue at the plinking range.
Every AR needs a few thermold mags
the 20s are pretty nice too...
dZ