The rugged and resilient SUPER GRIP ballpoint from Pilot.
The reliable retractable mechanism means that you're only ever one click away from being ready to write, and the rubber grip means you can write in comfort.
The tungsten-carbide tip is one of the toughest around, delivering the waterproof oil-based ink page after page - and once you've run out, you can simply refill the SUPER GRIP and keep going.
Avaialble in three colours: Black, Blue and Red. 1.0mm tip which gives a 0.31mm medium line. Refillable using Pilot RFNS-GG Ballpoint Pen Refills.