Use the Alpine Astronomical Baader Standard Dovetail Base to mount a variety of accessories onto your optical tube assembly (OTA) such as their multi-purpose quick-release finder bracket (MQR III & IV), the Witty 1 tangent assembly, or the Sky Surfer (III & V). The curvature of the base fits onto OTAs with radii from 130 to 400mm (5.1-15.7"). It is milled from a solid block of aluminum to maximize strength and durability, is treated with a black anodized finish, and comes with pre-drilled mounting holes that will fit OTA finder mount points.