BASIC Banknote Sleeves, to fit banknotes up to 158 x 75mm, pack of 50

A banknote's worst enemy is not time. It is the casual fold.

These are BASIC banknote sleeves in rigid PVC, sized to take a note up to 158 by 75mm, welded on three sides and open at the top so a note slides in and out without bending. The plastic is crystal-clear on both faces, so you can read a note front and back without ever touching it, and they come fifty to a pack. There are four sizes in the range; this is the middle-ish one, which fits a great many of the world's notes.

It is the no-kinking that earns Jonah's quiet approval. He once bought a box of secondhand books and found, pressed flat between the pages of a dull volume on drainage, a banknote that had been kept there so long and so carefully that it had not a single crease in it — flatter and finer than notes a fraction of its age. Whoever hid it understood something. A note kept flat keeps its dignity; a note folded into a wallet slowly forgets it ever had any.

The sleeve does the same job as that forgotten book, only on purpose.

Paper money survives best when it is left in peace and kept straight.