This is a finger grip, modeled after some of the older syringes. It's meant to slide onto a syringe and give you enough of a grip to help you push the plunger down. It was modeled to fit over a 11.7mm barrel and the finger holes are 24mm wide.
This was designed in Fusion 360 and I sliced it in PrusaSlicer with supports.
Please feel free to request additional uploads of files.
The author marked this model as their own original creation.