Double Color Cube Clay Beads, Random Mix 14mm PLEASE READ DESCRIPTION

The hole is a bit too small for beadable pens. If you twist and push downwards, it may still possibly fit on pens but it's not guaranteed, so self drilling is highly recommended. 

If you need a hand drill, here is the link for your reference.

https://www.beadablebliss.com/products/small-pill-acrylic-beads-7mm-by-9mm-%E7%9A%84%E5%89%AF%E6%9C%AC-1?_pos=1&_sid=0bacbc11e&_ss=r