NS would probably the trilux night sights that glock offers. they offer 3 kinds of night sights strait from the factory; trilux, meprolights and trijicons. MNS would be meprolights and TNS would be trijicons. i prefer meprolights.
Glock no longer imports into the US the G17L, G24 or G24C. however you can buy a complete G17L or G24 upper straight from Glock for $250. you can mount them on a G17 or G22.