3 ms·
https://eclipse.aas.org/eye-safety/iso-certification https://eclipse.aas.org/eye-safety/iso-certification says "The only ones that are safe for direct viewing o
by tgsovlerkhgsel 7y ago
https://eclipse.aas.org/eye-safety/iso-certification https://eclipse.aas.org/eye-safety/iso-certification says "The only ones that are safe for direct viewing of the Sun with your eyes are those of Shade 12 or higher."
(which are rare because they're too dark for most welding)
Other sources said 13 was the minimum. You're probably best off with a 13 or 14. I found 13 too bright.