Ghost ring sights?

[canadaman30]

What companies make these ghost ring sights, that look as if they sit in the groove of a scope base. Or who sells these things. Would like to try them out but can't seem to find them.

 

[jennis]

'scattergun technologies' (GRS) I have them on a couple of 870's , your best bet would be mail order from Cabelas or Midway USA failing a CDN source, maybe try Marstar/Milarm ???????