This is a set (one left, one right) of Type 1637 wheel hubs made by Al-Ko Kober for a Cobra trailer. These are the type with 4 lug bolts, rated at 500 kg each, as used on most Cobra trailers set up for 15-meter-span gliders.

Photos he https://photos.google.com/album/AF1Q...EsvnXZQxK-41ak

They came off a trailer whose owner converted to an axle with hubs that incorporated hydraulic braking. They are in almost-new condition, showing only superficial wear. Factory-new examples are listed on the Wings & Wheels website at $1040.

If interested, make an offer.