RoHS stands for Restriction of Hazardous Substances. RoHS, also known as Directive 2002/95/EC, originated in the European Union and restricts the use of specific hazardous materials found in electrical and electronic products (known as EEE). All applicable products in the EU market after July 1, 2006 must pass RoHS compliance. The substances banned under RoHS are lead (Pb), mercury (Hg), cadmium (Cd), hexavalent chromium (CrVI), polybrominated biphenyls (PBB), polybrominated diphenyl ethers (PBDE), and four different phthalates (DEHP, BBP, BBP, DIBP). RoHS 1600 DPI 1600 Battery powered Batteries Mouse ambidextrous Ambidextrous HP x4000, Ambidextrous, Laser, RF Wireless, 1600 DPI HP x4000. Form factor: Ambidextrous. Movement detection technology: Laser, Device interface: RF Wireless, Movement resolution: 1600 DPI, Buttons quantity: 3, Scroll type: Wheel. Power source: Batteries. Works on any surface http://www.digitalversus.com/computer-mouse/hp-wireless-mouse-x4000-p13359/test.html The Wireless Mouse X4000 is HP's latest laser sensor mouse, sold at an affordable price, and as such has earned a place in our reviews. HP Wireless Mouse X4000 Here's... No setup required; just plug it in, For both righties and lefties, Adequate for basic tasks (Internet, editing documents...), Softtouch body, Smooth movement Useless for games that require speed, Few buttons, Instep scrolling only The X4000 is fine for basic office work. It's inexpensive and glides easily over the table. But it may disappoint users who want something more out of their mouse, because it has only two buttons and its maximum speed is far too low for video gaming....