Cartridge rollerball with warning light at the end of the pen. This indicates when too much writing pressure is exerted and teaches how to judge the right pressure for fluid writing. Ideal for beginners and for people with motor difficulties. Base Senso uses replaceable rollerball cartridge 852 with ball tip, royal blue ink, erasable. Ink dries quickly and is smudge proof when highlighting it later on. The ergonomically designed grip is rubberised for elasticity and to prevent slipping, while large finger pads prevent pressure points. Equally suitable for both left-handed and right-handed users.