The 820542501 from Wurth Elektronik is a Disk Varistor. It has an AC voltage rating of 25 V, a DC voltage rating of 31 V, and a clamping voltage of 77 V. This varistor can withstand a peak pulse current of 1000 A and has a low power dissipation of 0.1 W. It has a reverse breakdown voltage of 39 V and an input capacitance of 7620 pF. It offers excellent absorption of surge impulses and operates from -40°C to +105°C. This RoHS-compliant varistor is available in a through-hole package that measures 44.5 x 16.5 mm and is ideal for 12-48 VDC distribution, 110-400 V power supplies, and leakage of voltage peaks.