I don't know, but most 'tank' type cuvette holders I've seen hold anything from 100 mm down, provided that the cell compartment is long enough.

Exactly!!! And that’s what I’ve been trying to say with the sales guy. If u look carefully at page 11 on the manual of Evolution 201 spectrophotometer thermo fisher scientific , there is a cuvette holder for cylindrical cells. The sales guy says that it’s only meant for 50 mm cells and he is trying to sell me something else - the solid sample holder. I don’t know how to explain to him that if he only had a look at the holder displayed on the page- it currently shows that it holds 100 mm but he says it’s 50 mm.please see the manual attached here. Page 11