Since late 2016 there have been more $200 million in orders for the American TOW (Tube-launched, Optically tracked, Wire-guided) missile. This is a system that entered service in 1970 and, obviously, continues to be popular. So popular in fact that two countries (Iran and China) developed and still manufacture clones of the TOW system. But there are enough users of the original to keep a weapon dreamed up during World War II and finally put into development fifty years ago.
The Iranian TOW clone, the Toophan ATGM (Anti-Tank Guided Missiles) has been heavily used in Syria by the Iran backed Lebanese Hezbollah force. Toophan is literally an Iranian copy of the TOW missiles sold to the Iranian monarchy in the 1970s. When the monarchy was overthrown in 1979 the rebels found themselves in possession of lots of modern American weapons, including plenty of TOW systems. By the 1990s Iran had managed to copy the TOW as the Toophan. By 2000 they upgraded it and are now supplying Hezbollah with dozens of TOW systems. Iran probably noted that in early 2015 Kurdish forces fighting in Iraq and Syria were using the Chinese HJ-8 ATGMs, which is the Chinese version of the TOW. Israel has also been using the TOW since the 1970s and now faces the prospect of fighting someone else (Hezbollah) who has it.
The original American TOW is still in service worldwide and over 500,000 TOW missiles have been manufactured so far and it remains in service with the United States military and troops from many other countries. All versions of TOW are shipped and fired from a sealed launch tube. That tube is placed on a MGS (Missile Guidance Set) that contains the gunner sight, with night vision, and operator guidance electronics. The MGS weighs 25 kg (55 pounds). The 1970 version of the missile weighed 19 kg (42 pounds) and had a 3.9 kg (8.6 pound) warhead. The latest version (TOW 2B or BGM-71F) weighs 22.7 kg (50 pounds) and has a 6.2 kg (13.5 pound) warhead that can defeat ERA (Explosive Reactive Armor) at targets up to 4,000 meters away. Nearly all ATGMs use shaped-charge warheads that penetrate most tank armor and are also effective against structures and unarmored vehicles.
The HJ-8 and Toophan are nearly identical to TOW 2 in size, weight, range and, according to the users, performance. Both TOW and HJ-8 use SACLOS (semi-automatic command line-of-sight) guidance. This system works by having the operator hold the target in the MGS sights and the missile will be guided to the target via wires that connect the missile to the launcher. The big problem is that the operator is often under fire and that sometimes makes it difficult to maintain aim. The next generations of anti-tank missiles were wireless and “fire-and-forget” which allows the operator to duck as soon as the target is identified by the MGS and the missile fired. Wireless versions of TOW have been developed but the cheaper, more reliable (and immune to jamming) wire system remains popular. This is especially if you are frequently using TOW as an infantry support weapon. This was a popular use in Iraq, where precise aim was important for urban combat.