Working on a tiny carburetor today (neighbour’s Honda generator) and used this weird little screwdriver. The centre section of the blade is spring loaded. When you insert it into a slot head screw, you click the end and it twist locks to the screw. Brilliantly handy to start screws in places you can’t reach into.,,,, I use it every time to put the plugs back into carbs after removing the synchronizing tubes. Second picture shows how the centre portion twist to lock in place. Once the screw is started, you just pull off the driver and finish off with a normal driver. Brilliant.
When I worked with an old electrician, he used it to start screws in electric panels (often live ones!). He gave me this one. Easily +50 years old. No idea who made them, faintly stamped “Made in USA”. Ideal Tool Co. maybe? Anyone know?