This pen is a four-color Black, Red, Blue and Green ballpoint pen that uses the Acro ink developed by the Pilot. The oil-based ink has 1/5 of the viscosity of conventional oil-based inks. The unique blend of ink and lubricants allows the ball at the tip of the pen to rotate smoothly by reducing friction. This creates an enjoyable, non-skip writing experience. The ink is satisfyingly pigmented and is also water-resistant. The pen has a unique rubber grip developed by Pilot that sports a tire pattern, which prevents your hand From slipping. The clip on the pen uses a coil spring with a "soft clip" Mechanism that can be clipped 100, 000 times without breaking, according to Pilot testing. Not only is it durable, The clip is extremely easy to open and use.