This is a set of Uniball Propus Window marker pens.

The Uniball Propus highlighter tip with a window - gives you a “window” to see what you are highlighting, drawing, or writing so that you can clearly mark your pages neatly. The "Propus Window" series has twin dual tips, one 4 mm windowed chisel tip and a 0.4 mm extra-fine tip. The extra fine tip is perfect for journaling and writing. Most highlighter’s have tips of 0.6mm or thicker, which can make it harder to write and also difficult to neatly highlight words. Made in Japan.