I put the Pilot Frixion Ball Erasable Gel Pens to the test to see if they're really worth it here's an in depth review.
Pilot FriXion Ball Eraseable Gel Ink Pen Review - The Gadgeteer
Pilot FriXion Ball Knock Retractable Gel Pen, 0.5 mm - Blue
Pilot Frixion Ball Erasable Gel Pen Review - Crewel Ghoul
Pilot FriXion Ball Knock Zone Erasable Gel Ink Pen Review — The
Heat and Friction Erasable Pen, Embroidery Transfer Pen, Erasable
Pilot Frixion Ball Erasable Gel Pen Review - Crewel Ghoul
My all time favorite planner pens: Pilot Frixion Erasable Pens Review
Pilot Frixion Erasable Gel Pen Overview
Pilot FriXion Erasable Pens: A Comprehensive Guide