EPCOS B32923C Metallised Polypropylene Film Capacitor, 305 V ac, 630 V dc, ±20%, 680nF, Through Hole

EMI suppression capacitors (MKP) X2 class
Very small dimensions
Self-healing properties
Plastic case, epoxy resin sealing (UL 94 V-0)
"Across the line" applications

Capacitors X class are designed for connecting directly across a mains supply, but should NOT be used in positions where failure of a capacitor would expose anybody to electric shock.