Fisher Space Pen Refill — 2-Pack (SPR4)

The Fisher SPR4 is the only refill we stock because it's the only one we trust. Pressurized thixotropic ink writes at -35°F to 250°F, upside down, on wet paper, and in zero gravity. Not marketing copy — actual engineering used by NASA since 1965.

Fits all Apex pens. Also fits most bolt-action and click-action tactical pens on the market.

• Fisher Space Pen SPR4 pressurized cartridge — 2 pack
• Writes in extreme temperatures: -35°F to 250°F (-37°C to 121°C)
• Writes upside down, on wet paper, over grease
• Medium point, black ink
• 7-year shelf life — buy a spare and forget about it
• Fits all Apex pens, Schmidt P8126 compatible housings, and most Parker-style threads

One pack keeps you writing for approximately 6–9 months of daily use. Two packs = a year of zero interruptions.