Stálogy 019 4 Function Pen

Stálogy's 4 Function Pen is ingenious. The pen has, as the name suggests, four functions - black, blue and red oil-based ink with low viscosity, as well as 0.5 mm leads. Refill cartridges can be found here, and it can be refilled with whichever 0.5 mm lead there is, such as Pentel Ain Stein.