Steel lugs and bottom bracket shell for framebuilding. For 1" steerer (31.7mm headtube), 28.6mm downtube and seat tube, 25.4mm top tube and 22.2mm round chainstays. Bottom bracket is English thread. Perfect for a classic Columbus SL build. Will have some shop wear and surface blemishes from the factory, and tangs may be slightly bent from storage. I have a few sets of these.