JohnK.BatesYou'll have a hard time getting a screen protector to adhere properly to a domed crystal.
Besides, you're unlikely to scratch it. I've got domed sapphire crystals on several other watches, including my daily wearer; the stainless steel bezel has a couple of deep gouges from where it has scraped against concrete walls, yet the crystal remains flawless after four years. Even though the peak of the dome reaches out above the bezel and definitely scraped the concrete as much as the stainless did.
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