Pilot Oil-Based Ballpoint Pen Refill, Extra Fine, Black [10 Pieces] BRFS-10EF-B Pilot Ballpoint Pen Refill BRFS Features: Pilot refill, BRFS series. 990 *Any thickness of BRFS series pen refills can be replaced.* (Example) A 0.5mm refill can be used in a 0.7mm pen. Specifications: * Ink: Low-viscosity oil-based ink (Acro Ink) * Part Number: BRFS-10EF (0.5mm), BRFS-10F (0.7mm) [Compatibility] * Multi-function pens 2+1 Evolt, Legno, Ridge, SR, Miyabi Emaki, Acro Drive, Slim, Custom Heritage 4+1, Acroball 2+1, 3+1, etc. * Multi-function pens 4+1, 3+1 4+1 Custom Heritage, 4+1 Ridge, 2+1 Ridge, etc. * Multi-color pens (4 colors, 3 colors, 2 colors) Legno Maple, 3-color ballpoint pen Ridge, Rotating 2-color, etc. [Compatibility] Because it is a 4C series refill, it can also be used in the following replacement refill models from other companies. Mitsubishi Pencil: SE-7, Tombow: BR-VS, Pentel: KFS7, KFS6, Platinum: BSP100S, Sailor: 18-0103, etc. * Refill Size: 0.5mm, 0.7mm * Colors: Black, Red, Blue, Green *Green is only 0.7mm* * Size: Total Length: 67mm, Maximum Diameter 2.3mm