Alder Alder

The label on this trailer says it is a Sporty, yet the person who owned it advertised it as and Alder. The snaps around the trailer, show that a cover was a part of the trailer. Unable to tell if the frame and the body are steel or aluminum. If you have any info on this brand of trailer, feel free to drop me a line and tell more.
UPDATE:
I recently acquired a Coffman Single Wheel trailer that I am restoring and while working on the site I noticed that this Alder trailer has the same frame and wheel assembly as the Coffman trailer. Take a look for yourself.
Found this ad on The Samba.  "One wheel trailer 1961 ALDER (60 lbs). It is a 1961 Alder Title says it 60 lbs. It is starting to carode in two small spots on the right lower middle side if you look you can see it. I have a vinal snap on top, sits up about a foot higher needs to be repaired (if I can find it)."

Click Images to enlarge!!!!