Originally Posted by HillRider

It's a Shimano UN55 cartridge and English threaded so it can't be reversed. I agree with Roger that it's way too long. A 127.5 mm is about the longest cartridge spindle Shimano ever made and it was mostly used on triple cranks that needed a wide chain line. The OP want to use a single chainring on a fixed gear and he needs a much shorter spindle.