Original knob for Hehr 4900 series windows and can be used on some roof vent operators too.

Original Hehr PN 008-202 or 008-203.

Choose from either a shorter 1/2" long shaft or a extended 7/8" long shaft, depending on whether you need clearance around window or vent frame obstructions.  

If you need even more extension, you can buy VTS-2530 extensions separately.