The quality Faber Castell with go! I wanted a pencil eraser size to fit easily in a very thin package. This one is perfect for this, with two side, one soft rubber (classic pink gums) and other gum "hard" (equivalent to the blue side of conventional gums). This erases everything well and on any medium, including non glossy papers. However, this does not erase the bic pens, except maybe those who are called "erasable" but I have not tried. Gums are rigid enough not to break if the gum is vigorously. So perfect for easy transport gum!