Pilot Frixion Synergy Knock vs Uni-ball R:E Erasable Gel Pen 0.5mm

The Pilot Frixion Synergy Knock is the more versatile pen. It comes in three tip sizes down to 0.3mm, eight ink colors, and a Synergy hybrid tip that keeps fine lines smooth. The Uni-ball R:E is a solid single-purpose erasable gel pen with a 0.5mm conical tip and a lockable push-button eraser, but it offers far less choice. Reviewers of the Frixion line praise the smooth writing and the eraser color coding by tip size. Both use thermosensitive ink that fades above roughly 140°F, so neither suits signatures or documents left in a hot car.

• Choose the Pilot Frixion Synergy Knock if you want fine 0.3mm or 0.4mm lines, several ink colors, or a pen that writes smoothly at small tip sizes.
• Choose the Uni-ball R:E if you want a simple 0.5mm black erasable gel pen with a push-button eraser that locks so you can rub hard without retracting the tip.