Best wide angle lens for the canon eos r?

Here is what the site says about that.

From Canon EOS R: Canon EOS R: A mirrorless camera by Canon with a 30.3-megapixel full frame sensor, announced in 2018. Canon's first full-frame mirrorless body, now a common used buy. Specs - Maker: Canon - Mount: Canon RF - Sensor: Full frame, 36 x 24mm, crop factor 1.0 - Resolution: 30.3 megapixels - Stabilisation: none in the body; use stabilised lenses for slow shutter speeds - Announced: 2018 - Type: mirrorless camera Focal lengths on it ...

From Laowa 15mm f/4 Wide Angle Macro: Laowa 15mm f/4 Wide Angle Macro: A macro lens by Laowa for Full frame cameras, 15mm f/4. An ultra-wide that focuses to 1:1.

Quoted from this site's pages.