The Republic of Korea has placed an order for an additional four 'B' variant Patrol Killer Experimental (PKX-B) to Hanjin Heavy Industries and Construction (HHIC). HHIC has previously been awarded a contract to build the first four PKX-B vessels out of 16 initial order, first of which was launched on 28 July, 2016. 

The contract was announced by the Republic of Korea's Defense Acquisition Program Administration (DAPA) on 29 June, stating the PKX-B vessels will largely be deployed to bolster maritime security near the Northern Limit Line (NLL) once these are in service. 

The 44-meter long PKX-B is powered by General Electric's LM 500 gas-turbine engines and Caterpillar Marine's Cat C32 diesel engines in a combined diesel and gas turbine (CODAG) configuration and is able to reach a maximum speed of 40 knots. The vessel is armed with a 76 mm naval gun, two 12.7 mm machine guns, and an aft-mounted 12-barrelled multiple launch rocket system (MLRS) that can launch 130 mm projectiles.