The Mojo's are really nice sights. I have two, one on a Yugo SKS and I got another for my M38 Mosin. It is a big improvement over the stock sight especially on the SKS coupled with the Williams "Firesight" to replace the front blade.
They have great customer support too. I emailed them about the long elevation screws and they got right back to me within the hour and said they would send me two shorter ones free of charge.
rjk2475, concerning the Norinco SKS:
I have two Yugo M59/66s, two Yugo M59s(the ones without the Grenade Launcher), a Romanian, an Albanian and a Norinco. The Norinco is much nicer quality than the Albanian, but a bit rougher looking metal work than the others. It's got a gritty trigger, but not any more than most of the other military rifles I have (the two M59s have really nice triggers, but they are well used and worn rifles). It shoots just as good at the best shooting SKS's I have (the Romanian and one of the Yugo 59/66s shoot the best BTW). They are all rock solid reliable. None of these have given me a peep or trouble once I cleaned them up and got all the gummed cosmoline out of them.
IMO, the Yugo 59/66 is the best deal out there for an SKS, but Norincos are great rifles too. Norincos aren't the bottom of the barrel. Albanians are.