I don't know. Mine is a £10 one I got off ebay. I'm not a machinist so not concerned with hyper accuracy. +/- 0.1mm is more than enough for me and mine seem to have got me here without ordering the wrong seat post or handlebars yet.
Go for the Maplins ones if that is convenient. You can then even stab one of them in the eye* when it goes wrong
I don't know. Mine is a £10 one I got off ebay. I'm not a machinist so not concerned with hyper accuracy. +/- 0.1mm is more than enough for me and mine seem to have got me here without ordering the wrong seat post or handlebars yet.
Go for the Maplins ones if that is convenient. You can then even stab one of them in the eye* when it goes wrong
*return it