The main function of the Pilot Birdy Switch is a 0.5mm mechanical pencil. The pencil works great, and I haven't had any issues with it. I'm guessing it's the same mechanism that Pilot uses in their other multi pens, and I've always been happy with those. This one is just wrapped in a thin aluminum shell that makes it seem like you're writing with a long, bare multi pen refill instead of a real pen. But, that's what affords it the transport and utility points. To extend lead, click the cap. To retract it, hold down the cap and push the lead back into the tip. Unlike a lot of mechanical pencils, this one does not sport a tiny eraser or lead clog remover.
Instead, removing the cap reveals a tiny ballpoint pen. Honestly, I picked this pencil up in a JetPens order without fully reading the description. I just bought it because I was on a mini mechanical pencil kick, and all I needed to know was that it was a mechanical pencil. It wasn't until I got the pen, used it for a while, and then became curious how much lead was in the reservoir that I actually removed the cap. I was stunned to find the ballpoint tip! What a pleasant surprise. Of course, I tried writing with it and discovered that it's pretty smooth. I don't know for sure if it uses the same ink formula, but it feels a lot like the Pilot Acroball 0.7mm refill. This thing is tiny! Unfortunately, it only comes in black, but you can at least pick up refills.