The Fotodiox rear lens cap is a spare or replacement cap specifically made for all Canon RF mount lenses and adapters. The plastic cap protects the rear element and mount of the lens or adapter against scratches, moisture, dust, and fingerprints when the lens or adapter is not attached to the camera. The cap attaches securely by simply twisting onto the lens or adapter. Compatible with Canon RF mount Mirrorless cameras - Popular models include: EOS R, EOS RP