Square Burnerd Multisize collets
£45
Pair of two off British made Burnerd square multisize collets, one covers 16-19mm (5/8-3/4″) & the second covers 19-22mm (3/4-7/8″), price is for the pair.
These fit the common size Burnerd range of Multisize collet chucks that also cover the round range to 1.5″. (several sets on my this web site)