This is a locking plate designed to lock the screw on a standard Helping Hands benchtop tool to allow for one handed tightening or re-adjustment. Normally when trying to cinch down the wing nut the screw will also turn, requiring you to use two hands to attain the level of tightness that you are trying to get. There are times when you loosen the joints and the object being held will fall suddenly and possibly be damaged or the opposite where you want to keep the object in the perfect position while tightening, but when you are mid loosen or tighten the object will shift or droop out of the optimal position when you have to use both hands to tighten the joint. This locking plate allows you to maintain control over the object at all times, using one hand to keep the object steady and correctly positioned while you can use the other hand to freely tighten the join to the desired tightness without the possibility of damaging your work or have it fall out of optimal positioning.
As a L2 lab technician, I use this tool every day holding PCBs under my microscope while I perform nano hand soldering on 0201 surface mount components and smaller. Having the certainty that these boards will not shift or droop while working, or being able to make small changes quickly and easily has made my job much easier and safer. Seeing that a lot of the components I work with are very fragile and potentially valuable, being able to maintain control over them while re-adjusting is also very important to me and was one of the leading reasons for designing this part.
I hope that this design can help many other hardworking technicians and hobbyist out there to make their work space a safer and more efficient environment.