This is an upgraded Velvet Thruster drive screw. This steel screw is included on the Auto-Solo - Velvet Stroker Model. The steel screw is required to operate the Stroker head and Vagina insert, it is unbreakable. It is a faster stroke speed, approximately 200 strokes per minute, and a little shorter by about 2.55" of stroke length.
Perfect for our Auto-Solo.