Which gel refills would fit the Sheaffer 300 ballpoint? Tape was my first solution too. now i already own a 0.5mm pen and i want to be able to exchange the refills. It is easily done using a box cutter because the body is plastic. Monteverde refills are nice. If you cut a small piece of plastic tubing to fill in the backspace, any Pilot G2 refill work. https://www.shapeways.com/product/HC8VS2R45 If so, I would recommend to Moleskine gel refills or the Monteverde gel refills. They also churn through ink quickly so most people end up needing to purchase them in quantities but I find its the best of both worlds — fine lines in a pen that only accepts a D1. - International Association of Penturners, http://www.pensandplanes.com/blog/pen-hacks, The Epic Refill Reference Guide - International Association of Penturners, https://www.amazon.com/Bettoni-Rollerball-Pen-PROMOTIONAL-CUSTOMIZED/dp/B01GHAYP52/ref=sr_1_8?s=office-products&ie=UTF8&qid=1475790113&sr=1-8&keywords=bettoni+pen, refill converters that will accept D1 refills, Jazz Up Your Jotter: Parker-Type G2 Refills – Danielle Hooke Goodbody, Get to the (needle)Point | The Poor Penman, The Render K by Karas Kustoms | The Poor Penman, Moleskine Click Ball Pen Review | The Poor Penman, Video-Review: Stilform KOSMOS Pen - Scrively - note taking & writing, http://www.spacepen.com/blueinkfinepointfisheruniversalrefill.aspx, Review: Parker Jotter | Comfortable Shoes Studio, https://www.shapeways.com/product/HC8VS2R45, Everything You Always Wanted to Know About Refills* (*But Were Afraid to Ask) - Bleistift, https://us.moleskine.com/roller-gel-refill-plus-black/p0361, Help Understanding Refills - Page 2 - International Association of Penturners, Baron Fig Squire "Mysterium" Pen | Calligraphy Nut, The Epic Refill Reference Guide: Rollerball, Gel and Ballpoints, A Beginner's Dive into Ring-Bound Planners: Part 2 - Planner Sizes, Pencil Sharpener Review: Høvel Pencil Plane, Faber-Castell Scribero Gel Ink Roller Refill, Fisher Space Pen Refill, PR Series- Colors (Bold, Medium, Fine), Fisher Space Pen – Universal Ballpoint Refill, Foray (Office Depot) Ballpoint Refill for Parker (Medium), Monteverde Soft Roll- Colored inks (Medium), Monteverde Soft Roll- (Superbroad, Medium, Ultrafine), OHTO Needlepoint Ballpoint Pen Refill PS-807NP, OHTO PS-205NP Extra-Fine 0.5mm Ballpoint Pen Refill, Parafernalia Ballpoint Pen Refill NO LOGO, Parker Ballpoint Pen Refill (Broad, Medium, Fine), Parker Quinkflow Ballpoint Pen Refill (Medium, Fine), Pelikan Giant Ballpoint Pen Refill 337 (Broad, Fine, Medium), Premec Parker-Style G2 Gel Refill (0.4, 0.5 and 0.7 mm), Retro 51 Tornado Roller Ball Refills (REF5P) (Made by Schmidt), Schmidt P900 B Ballpoint Pen Refill (Broad, Medium, Fine), Schmidt P950M Megaline Pressurized Ballpoint Pen Refill (Medium), Schneider Express 735 Pen Refill (Broad, Medium, Fine), Schneider Slider 755 Pen Refill (Extra-Broad, Medium), Visconti Ballpoint Pen Refill AA49 1.4 (Broad), Visconti Gel Refill (Broad, Medium, Fine), FORAY (Office Depot) Pen Refill For Schmidt Rollerball, Monteverde Spring-Loaded Tip Fineliner Refill G62, Schmidt Capless Rollerball 8126 and 8127 (shorter models can work with an extension hack), Schmidt 888 Safety Rollingball Ceramic Plastic refill, Schmidt 5888 Safety RollingBall Ceramic Metal Tube refill, Schmidt 5285 Safety Rolling Tube Needlepoint Tip, Pilot Hi-Tec C (available in 0.25, 0.3, 0.4, 0.5), Pilot G-Tec C (same as the Hi-Tec C but renamed for the American/European market), Acme Black 4FP Four-Function Pen Ballpoint Pen Refill, Acme Highlighter 4FP Four-Function Pen Multi Functional Pen Refill, Aurora Mini Medium Point Ballpoint Pen Refill, Monteverde Soft Roll Ballpoint Pen Refill – D1 (628), Ohto R-4C7NP Needle-Point Ballpoint Pen Refill, Rotring Tikky 3-in-1 2-Color Ballpoint Refills, Uni SXR-200 Jetstream Ballpoint Multi Pen Refill (0.5 and 0.7mm), Zebra Sharbo X Ballpoint Multi Pen Refill Component – D1, Zebra Sharbo X Gel Ink Multi Pen Refill Component (0.4 and 0.5mm) – D1.