WARNING: NEVER USE ECLIPSE GLASSES TO LOOK THROUGH TELESCOPES, SPOTTING SCOPES, CAMERA LENSES, BINOCULARS, OR ANY LENS SYSTEM THAT ARE AIMED AT THE SUN! INSTANT AND IRREVERSIBLE DAMAGE TO YOUR EYE(S) WILL OCCUR!
Eclipse Glasses and over-the-lens solar filters that are ISO 12312-2 Rated are 100% safe for direct observations of the Sun, provided that they are used properly.
But you should NEVER use eclipse glasses to view through telescopes, binoculars, or any lens or mirror system that DOES NOT have safety-certified over-the-lens solar filters. Scott Roberts from Explore Scientific demonstrates how the energy of the Sun focused through lenses will INSTANTLY DAMAGE eclipse glasses and your eye(s).