Philip, in this case the pictured XS Ghost Ring Sights are correct.

upc crosses to ghost ring sights see ******When you absolutely must be able to rely on your shotgun in an emergency, the choice is obvious. A first choice duty weapon for police and the military worldwide, the Mossberg 590A1 is the only pump action shotgun to survive the rigors of US military Mil-Spec 3443E testing. This edition for left handed shooters features a heavy walled 20" barrel and a magazine capacity of 8 rounds.
Specifications and Features
Mossberg 59815
12 gauge
Left hand pump action
20" heavy walled barrel
Fixed cylinder bore
8 rounds capacity
************XS Ghost Ring sights
Synthetic stock
Length of pull 14.25"
Overall length 41"
Weight 7 lbs
Parkerized