At the opposing end we have incorporated a 46-48 HRC steel ‘ball’ tip for emergency glass break applications. The entire shaft of the pen is constructed from 6000 series, non-reflective; black anodized aluminium for extreme longevity and wearability. The TWI-02 includes an O-ring seal making it completely waterproof when the cap is screwed down over the writing tip; the opposing end has a ‘click on’ feature for the cap. Knurling at key points along the pen aids a positive grip. When it comes time to replace the refill the TWI-02 will accept standard Parker and Fisher Space Pen refills, we have found these refills to offer superior performance. SPECS: Description: Tactical Pen Action: Screw Cap Finish Pen Body: Anodized Finish Pocket Clip: PVD Ink Cartridge: Contains Pressurized Ink Cartridge. Carry: Pocket Material: Aluminium (6061-T6) Material Pocket Clip: Stainless Steel Material Glass Breaker: Steel Diameter: 0.54” (13.70mm) Overall Length: 5.86” (149mm) Overall Weight: 1.83oz. (52g)