This is a holding screw driver/screw starter that I've had for quite a few years. Contacting the suppliers I normally use don't have /can't find. I don't need it a lot but this one workd better than any others I've ever had. It is a straight bit on one end, phillips on the other. The center rotates to lock onto the slot. The each end can be twisted and locked into the unlocked position so you can push it into a screw head and lock the tool releases and locks into the slot.