Complete A2 rear sight kit. This kit requires assembly and will mount on an A2 upper receiver. Includes: A2 Rear Base Lug A2 Rear Sight Aperture Rear Base Flat Spring Rear Base Windage Knob Screw Rear Base Windage Knob Rear Base Spring Pin Rear Base Spring Rear BaseBall Bearing Rear Base Index Elevation (8/3) Rear Base Elevation Knob Rear Base Elevation Knob Spring Rear Base Spring Pin Rear Base Index Screw Mfg: Luth-Ar