Beads of Contemplation

This strand of eight wooden beads, each cleverly carved with geometric patterns, hangs from a stout length of cording. The beads store ki energy placed into them, holding the ki until you use it. The beads can store up to 8 ki points. At the end of a short or long rest, you can place ki energy into the beads by touching them and expending a number of ki points equal to half your proficiency bonus. While wearing or carrying the beads, you can use a bonus action to remove any number of ki points from the beads, regaining that amount of ki points and freeing up space in the beads.

Source: Tome of Heroes · OGL-1.0a · 5.1