HMM Rule One - Pen & Ruler Tool for Designers: Multi-Use, Sleek Aluminum Bookmark with Interchangeable Heads (Ballpoint, Stylus, Lanyard), Signo Refill

Item is well made and comes in nice packaging. Writes nicely (fine lines). Lightweight and not too bulky when in pocket.

According to Jetpens this is the Original refillUni UMR-83 Gel Pen Refill - 0.38 mm - Black

After a year of use, the very end of the e black edges of the octagon have worn to an aluminum silver from constant rotation: the black color has worn off. Also one edge of the ruler. But, I’ve used the pen very heavily, thrown into bags etc. So ymmv.Also, I've been unable to find a ball point pen cartridge to replace the original after it ran out of ink. The ruler does NOT use the Schmidt P900 Parker Style Refill that HMM uses in its similar product HMM Slide. It doesn't fit: I found that out the hard way. I've been using a knife to carve other refills to fit, but that's getting old and I'm about ready to give up.If anyone knows what pen cartridge Rule One takes, please let me know here.Apart from that, it is a beautiful product and a joy to use -- or was until the black and the pen wore out.

El diseño del boligrafo no es comodo al escribir, no es ergonomico sibvas escribir demasiado.