JB offers 3-1/8" (80 mm) illuminated gauges. The glow-in-the-dark dials store energy to emit light in dimly lit or dark applications. The R-410A only gauges are not glow-in-the-dark due to their pink dial. The illuminated large gauges are also available with 1% accuracy rating. Gauges are sensitive instruments and should not be subjected to pressures beyond scale. Made in the USA.