These are adapters made to work with Cricut machines and allow you to use Sharpies, InkJoy pens, etc. rather than the Cricut branded markers. 

Currently supported pens are:

• Sharpie (Classic)
• Ultra fine point sharpie (the pen style sharpie)
• InkJoy (gel 0.7mm)

All of the adapters are designed to be printed from 95A tpu.

A ‘universal’ adapter designed to fit multiple pen sizes is coming soon (currently still a work in progress)