With over 54 years of experience, Alvin is one of the primary sources for drafting supplies and drawing equipment in the country. Together with this core group of products, we continue to meet the needs our customers with our expanding range of fine art, hobby and craft supplies, our large selection of drawing room furniture, and our wide assortment of exclusively-designed products. TOMBOW-Dual Brush Pen Open Stock. This dual brush pen has a versatile and flexible nylon fiber brush tip on one end that creates medium or bold strokes by simply changing brush pressure. The fine tip on the other end is for smooth straight lines or writing. The water based ink is blendable; odorless and non-bleeding. Acid free and non-toxic. Imported.