I remember a while back that somebody was looking for an accurate tire pressure gauge. Came across this advertisement stating .05% accuracy which is pretty dang good. I don't own this tool or know of its quality.
Precision Digital Tire Inflator & Pressure Gauge (0-160 PSI), Extreme ± 0.05% Accuracy s-580eMulti-Air Chuck Kit
Precision Digital Tire Inflator & Pressure Gauge (0-160 PSI), Extreme ± 0.05% Accuracy Milton Industries Presents the first of its kind…. Precision Digital Inflator Gauge The Precision series offers a variety of features which makes it the ultimate tool
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