It's never a bad idea to have some extra pen refills. The compact size of the perfection series of pens means the refills are smaller and run out faster than a standard size pen. The price we pay for compact utility.

A refill for Perfection Bullet Ballpoint Pens and Bullet Perfection light Ballpoint Pens.  

Dimensions: φ2.3mm x (H)67mm

4C (D1) Needle Tip/ 0.7mm Nib/ Permanent Black Ink