That’s a Block 1B Phalanx CIWS. The major exterior differences between it and earlier models are the reinforced barrels assembly and the FLIR/video pod on the left side. The Block 1B has been optimized to engage surface targets such as boats and slower aircraft like helicopters.
Here’s a summary of the Phalanx’s evolution:
Much more info on the Block 1B and more at CIWS now does surface targets, too.