as some others have mentioned, they are basically identical to the Troy guards. They used to be priced the same as Troy, but Troy recently dropped their prices and now they Troy is substantially lower. As with Troy, they are a high quality rail I m not entirely sure why, but they arent as popular with people as are DD, LaRue, or Troy. I have a Stag 2hT upper and they came standard on that model. It seems to me that the majority of people Ive met who had the Samson guards had them because they are on some Stag models. Aside from that you dont typically see a lot of people using them.
Basically I look at rails in four groups (tiers for the chart junkies).
The first tier is the $250+ range (for carbine rails). This is DD, LaRue, Samson, KAC, ARMS. Out of those groups the DD and LaRue are about even. I think DD is more poular of the two. I dont think that the others are worth the price when compared to either DD or LaRue. They are all heavy compared to the DD. Most may match DD in price, but not quality.
The second tier is basically 175-250 range. I think of Troy and Spikes in this group. This is truthfully the place the Samson should be. Since they are in the "top tier" however, they are overpriced.
The third tier is <125-175 range. I think of YHM and MI as being pretty equal.
The fourth tier is <100 and I think of UTG. I wouldnt purchase anything in this tier.