InkOwl Toner Refill Kit for HP CB540A, CB541A, CB542A, CB543A (125A) (4-Pack, with reset chips) Includes 4 bottles of Ink Owl premium formulation toner, 4 spouts for easy pouring, 4 reset chips, easy-seal tape along with detailed, graphic instructions. To refill this cartridge model, you'll need to pierce holes. To do so, it is highly recommended that you use a laser cartridge holemaking tool designed for this purpose. The use of any other tool, including a drill, is not recommended to avoid damaging sensitive internal components. You can then use the provided easy-seal tape to seal the holes. To get the tool: http://www.amazon.com/dp/B008J4P5JU For the proper functioning of the refilled cartridges, we have included reset chips. Our instructions will guide you step-by-step through the entire refill process and include pictures showing you exactly where holes need to be pierced and will show you how to install the replacement chip. Includes 55g of black toner powder and 45g of each color for the full 2200-page yield of black and 1400-page yield of color (at 5% coverage) just like the original HP cartridges.