The last essential keychain tool I want to talk about it the True Utility Telepen.  It's a stainless steel telescopic pen that shrinks to 50mm when closed and extends to a comfortable 115mm. When fully open, it is easy to hold and write with and closed you'll hardly know its there. Like my 2 other keychain tool recommendations, this is an everyday carry (EDC) type of item that you will find useful. Think of how many times you struggled to find a pen?

You won't write a multi-page letter or novel using this pen but for simple tasks like taking short notes, signing a check or filling out a form, its perfect. 

The kit comes with 3 refills but you can always cut a bic refill once you run out.