If you've run into some odd bow-tie shaped screw slots on your window or door hardware, you have probably discovered clutch head screws.  They were used on Chevy trucks and other GM vehciles from the 1940s through the mid-1960s.  Clutch head screws were also used in mobile home and travel trailer manufacturing from the 1950s into the 1970s.  Clutch head screws are ideal in a vibration application because they can be torqued more than standard screws when installed. 

To remove those old screws, you're best off using a screwdriver bit of the same shape and size.

Our set of clutch head bits includes the four most commonly used sizes on vintage travel trailers: 5/32", 3/16", 1/8" and 3/32" sizes. You can check size by measuring the maximum diameter in inches of the slot.

The bits fit in your power drill or a hand screwdriver that accepts interchangeable 1/4" hex bits.