The Pilot Birdy Switch multi pen is designed as a highly portable pen/pencil combo. With its small diameter, it would make a great choice as an EDC pen, somewhat along the lines of the TEC Pico Pen. It is a longer and wider than the Pico, but it is sleek enought to fit almost anywhere the Pico would.
At first glance, the Birdy looks just like a skinny mechanical pencil. With the cap posted on the clip end, that is exactly what it is. It functions just like a normal mechanical pencil - clicking the cap down extends the lead. Pop the cap off and post it on the other end and that exposes the ballpoint pen for use. I was a little concerned with the clip position when using the ballpoint side, but as it turns out, the clip helps out with gripping the pen. With a barrel this skinny it can be tough to grip while writing, but placing the clip between my thumb and index finger improved my handle on it.
Performance wise, the ballpoint writes very cleanly. There is nothing I hate more than a clumpy, messy ballpoint, so cleanliness is always a key for me. The pencil is nice as well, but being the side without the clip, I found I couldn't grip it as well. One note on the pencil though - there is no eraser. That phases me none, but I thought I would mention that. The only other negative I can find it that it is currently out of stock at JetPens. They do have a button on the page where you can be notified when it is back in stock, so be sure to set that up if you are interested.
Click here for the XL review.