I have for sale the Synta Dual Axis drives for the EQ4 and similar mounts (SkyView Pro, G5, ...). It also will work on the GP/GPDX as that is what I had them on. Works very well for visual use and tracking is very accurate. Not recommended for astrophotgraphy. I upgraded to the Vixen set for astrophotography so I don't need these. On/off switch is a little tempermental at times but in otherwise excellent conditon. Comes with mounting hardware, clutches and battery pack (4 D's not included). New they are $119 plus shipping from Orion. I will sell these for $60 plus actual shipping.