Posted here for folks not on Reddit or Twitter… a ragtag collection of MPs and one stray BP that sport knurling on the cone. Some for for twist-propell mechanisms. Others are to ease the removal of the cone for maintenance.
• Tombow SH-500LG 0.3mm - there are versions without the knurling.
• Unknown model 0.7mm with rubber coated body. Got this from eBay Spain.
• Unknown model 0.9mm - twist propel with 40cm telescoping body. D1 ballpoint under the top cover.
• Sun-Star Shapuru (Sharple) 0.5mm - cheapie resin chuck model with some nice styling. Standard version comes with a black button; the eraser version was for a J-pop souvenir with a removable fancy clip.
• Faber-Castell Datagraph 9588 0.9mm - twist propell, probably used for computer data entry cards. Love the retro OCR font.
• Platinum Pro-Use 171 0.9mm - Last of the Pro-Use line?
• CdA Fixpencil Metal F-S 0.5 - With built in adjustable cushioning.
• Eagle Turquoise 3375 2.0mm
• Righella Mini-matic - this is a cheat because the knurling is more like a grip, but I don’t have any other pens with this kind of feature