This is a PTFE tube holder that attaches to the front of the Anet A8 extruder motor when used as a Bowden extruder. This easily organizes your tubes so you can put them into the extruder when needed. Used for multiple colors or filaments. I use it to hold the tubes coming out of my dry boxes. It holds up to 6 tubes.
There are two versions one that has a small tip at the top to hold a cap from the tube that is loaded. The version with "No Cap" does not have the tip for the caps in case you don't need it. The tip size is the same as the tube size so any cap should fit on it. The caps I use are an optional item from this thing: https://www.thingiverse.com/thing:3172330/files