This is a mounting block to mount a Sidewinder on the print head of a CR-10 and all the compatible print heads, like Ender3. It requires no modifications to the print head.
This mount is only for the Nimble Sidewinder, if you want a mount for the standard Nimble, have a look here.
The mounting block clicks into the print head housing and the screw clamps it down. The screw replaces the bowden connector on the hot end. No modifications are needed to the print head.
All the green parts in the image are made separately and will be sent to you directly via UPS. And of course, you already have the print head.