Similar to the ADR, the ADR-X mount is designed for mounting 30mm tubed telescopic sights onto a flattop style AR-15 rifle. The 3-inch offset of this cantilever mount positions the scope in a forward location, allowing the correct eye relief and head placement on an AR-15. The extended 3-inch cantilever on the ADR-X provides an extra inch of offset compared to the ADR model and is best suited for scopes with four inches or more of eye relief.