The seller has called it a multi paneled jacket even though it isn't really. Never seen a collar buckle like that before, added later? I hope he doesn't reverse it on a regular basis!
http://cgi.ebay.co.uk/ORIGINAL-IRVIN-FL ... 500wt_1181
http://cgi.ebay.co.uk/ORIGINAL-IRVIN-FL ... 500wt_1181