30 Days Hasslefree Return Pilot Frixion ball slim gel pen features a slim body and 038 mm fine tip It is perfect for daily writing as well as adding annotations in a tiny margin on your notebooks or textbooks Pilot Frixion series is the best erasable pen on the market Pilot makes it with advanced technique on ink. This 038mm refill is compatible with the Frixion Slim Related Products Frixion Ball 3 Refill This 05mm refill is compatible with the Frixion multifunction ball series (eg Frixion ball 3 slim & 4) Ballpen refill (RF) This refill is compatible with the BKT1SR. Products search Menu MENU MENU.