SAVES YOU TIME & BACK PAIN - Attach one deflator to each tire stem, which halts air flow once the set PSI is reached. No Need to Deal With Valve Cores or Monitor Each Tire Individually. PRECISION ACCURACY - Each Tire Deflator is Individually Calibrated With an Accuracy of +/- 2 PSI, Specifically Designed for Quick Air-Down Setups for Off-Road Conditions. PRESET YOUR DESIRED PSI - Set Your Preferred PSI Anywhere From 10 to 30 for Optimal Performance in Sand, Snow, or Rocky Terrain.