Nitrous Express 15509 D-4 0-1500 psi N2O Flo-Thru Pressure Gauge High accuracy nitrous pressure gauge and a billet aluminum manifold Two 1/8 NPT ports allow you to connect the nitrous gauge as well as another 1/8 NPT accessory in-line with a D-4 line Measures from 0 to 1500 pascals per square inch