Downtube braze-on bolt on barrel adjusters. I have the same ones, OEM part for aftermarket power barcons. I once had the good fortune to buy a set of NOS barcons and they came with those, I like the shape, it's just a little different than shimano, a little narrower and more pointy.
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1 Super Record bike, 1 Nuovo Record bike, 1 Pista, 1 Road, 1 Cyclocross/Allrounder, 1 MTB, 1 Touring, 1 Fixed gear