TEC Accessories Ko-Axis Rail Pen Black Easy Refill No Accidental Retraction
4.29" overall. Pocket clip. Rectangular shape for writing comfort. 6mm low-profile body. Compatible with common D1 "multi-pen" (TEC02, TEC03), Fisher Space Pen (FP171112, FP171211, FP171419), and Rite in the Rain (RITR37R) refills.