The One Shot system offers a flexible and portable system for stenciling on both porous and non-porous surfaces. Easy stenciling system works on rough and smooth surfaces. Convenient for remote projects and job sites. No-mess, durable ink cartridge is fully disposable. All ink colors meet government ink specifications TT-I-1795A and CID A-A-208 Type 4. Seven highly visible colors meet CONEG and SARA standards. For indoor and outdoor use. Each Oneshot unit comes with roller, durable plastic storage case and one black ink cartridge 125 ml (4.23 ounces). How to use the Oneshot system Step 1: Insert the Oneshot roller into the ink cartridge. This action pierces the polypropylene membrane in the cartridge, allowing the ink to flow into the applicator. Step 2: Shake gently. Press the ink valve button to dispense ink internally through the applicator. You may have to press the button repeatedly until ink flows. We suggest you start rolling the roller on a practice surface like cardboard until you have the desired flow of ink for the surface being stenciled.