This LM8UU holder is designed for minimal footprint on a laser cut Y carrier. The screws are captive under the LM8UU and since it is printed on its side, it's strong. It needs to be printed on its side so that you can force an LM8UU to be held by the part very tightly. The hole is undersized and it will require a bit of force in order to get your LM8UU to fit.
I modified this part because I keep my Y axis rods spaced quite far apart, and the same with my bed springs/screws. All of the other ones with "wings" crossed the path of my adjustment screws and I needed more clearance. Since I also mount my power supply under the front of the Y axis, so I couldn't fit the screws to tighten up the LM8UUs without hitting my power supply.