GP-series tripods are designed to carry Vixen Great Polaris-series mounts and Vixen Fork mounts with half-pillar. The GP-series includes the GP, GP-D(X), GP-E, GP-D2, and GP2 equatorial mounts.
While every tripod here will fit any Vixen GP-series and Vixen Fork mount half-pillar, the short AL90 tripod is recommended for mounts carrying reflectors and the Vixen Fork mount with half-pillar. The heavy-duty HAL110 tripod is great for any scope that requires added stability; it is the best mount to handle the greater weight capacity of the GP-D(X) / GP-D2 mounts.
GP mounts can not carry Sphinx heads. The tripod head has a 60mm diameter depression that is 20mm deep with a M10x1.5 tightening center bolt.