Chinese frigate Huaiyin (513)

The class have four anti-ship SY-1s in two twin-box launchers, armaments consisted to two single 100mm dual-purpose hand-loaded guns with fire control by a very simple stereoscopic rangefinder, limiting the guns to effective fire against surface targets in daylight/clear weather only.

This met a PLAN requirement for air-defence ships to accompany the surface-warfare Type 051 destroyers.

The Type 053K was originally intended to have three screws powered by a combined gas-turbine and diesel engine, with a speed of 38 knots.

However, technical constraints forced the Chinese to settle for a diesel engine, powering two screws for a maximum speed of 30 knots.

The Type 053Ks were armed with HQ-61 surface-to-air missiles, launched from two twin-armed launchers; these did not enter service until the mid-1980s.