Capital ship turrets (also known as capital turrets, or informally, cap turrets) were laser cannons commonly mounted on starships and space stations for defense against capital ships. They were presumably similar to, or possibly a variant of, the turbolaser.
Both the Trade Federation and Sabaoth Squadron made use of capital ship turrets. Several defended Spacestation 1138 in the Karthakk system, and each Sabaoth Destroyer was armed with six turrets, in addition to anti-starfighter laser turrets. These weapons were powerful enough to pose a threat to Mere cruisers, and during the orbital First Battle of Geonosis, Adi Gallia and her Jedi pilots made it their priority to destroy all capital turrets on three Sabaoth Destroyers in order to aid the Mere Resistance.