Fabulous! is the best way we can describe these guys. Homemade by someone – unfortunately we don’t know who – with obvious engineering skills, we suspect they date from the 1960s, an era when commercially available nuts were embryonic, slowly replacing real nuts (as in nuts and bolts) that had been used for a decade or two, to jam in cracks to protect rock climbs. Guys with engineering skills and access to a lump of aluminium would make their own versions, in this case ‘jumbo size’ with viking nylon rope. We bought these on e-bay in 2023 for a few pounds, very happy as a result.