Taiwan is buying about a hundred MGM140 ATACMS (Army Tactical Missile Systems) artillery rockets from the United States. Taiwan does not have the M270 MLRS rocket launchers, which the ATACMS is launched from. Instead, Taiwan built its own, and much cheaper, version of MLRS; the RT2000. This system is close enough in size to MLRS that the ATACMS canister (for transport, storage and firing) will fit.
Taiwan is getting the ATACMS equipped with a 227 kg (500 pound) high explosive warhead. The U.S. used over 700 ATACMS in Iraq and Afghanistan. These rockets use GPS guidance to hit targets up to 300 kilometers away. Sort of like the popular 500 pound JDAM smart bomb used by the air force, but not requiring an aircraft to deliver it.
When the U.S. Army first introduced its long range ATACMS rocket 24 years ago, it designed fancy warheads that distributed lots of smaller bomblets. While these worked, there was always a problem with some of the bomblets not self-destructing, and later going off when civilians, or American troops, came along. Not a popular weapon. Then, when a version, with GPS guidance and a single, 500 pound high explosive (or "unitary") warhead was introduced, it proved very popular. These rockets cost about a million dollars each. A 500 pound JDAM costs about $28,000, although you can add a few thousand dollars more to cover the expense of operating the jet bomber that delivered it.
The ATACMS is a 610mm rocket that fits in the same size container that normally holds six 227mm MLRS rockets. It has sufficient range to reach Chinese coastal targets.