These are dense 3D printed sturdy Rack Ears for Behringer 3U synths Cat, Wasp and Model D synths.  Each ear is labeled L and R respectively.

These ears come with inserting holes on the left and or right side to allow patch / audio cables to go in through the left and/or right side let me know. 

Also while these are not metal like the official ones, because they are not metal and yet still very sturdy, they are much easier to modify once you have them in your setup.  

If you're putting the synth in a rack with gear that are deeply seated it is advised to use L shaped audio cables to keep the profile slim. If it's in a rack with other shallow gear you can use normal 1/4" straight cables. I decided it was better to keep the profile slim than waste rack space to compensate for the needed extra clearance for straight audio cables.

NOTE: lol, this is just the rack ears. This is not for my Cat modeling the items. :)