Afghan gun merchants can't get enough German pistols for their customers. The most popular model is the Walther-P1, a compact 9mm weapon once widely used by German officers and police (a Walther was the favorite of fictional superspy James Bond). Fortunately for the Afghans, Germany donated 10,000 used Walther-P1s to the Afghan police three years ago. Since then, many of these have been "lost" or "stolen" by the cops, and ended up in local gun shops.
NATO is learning that giving Afghan police and troops high quality weapons backfires. That's because there is, and always has been, an active marker for weapons in Afghanistan. Although most Afghan men cannot afford it, most would like to own a weapon. And those who can afford it, want the best weapons available. This has led to many Western rifles and pistols, donated to the Afghan security forces, disappearing into the local arms trade.
One solution for this is to just equip the Afghans with older Russian weapons (AK-47s and Makarov pistols). There are a lot of second hand Makarov pistols coming on to the market, as the Russian police upgrade to more modern models. The 9mm Makarov was introduced in 1951, to replace the 1930s era TT-33 pistol. This beast weighed 854 grams (30 ounces) and fired a puny 7.62mm bullet from an 8 round magazine. The (then) new Makarov weighed 730 grams (26 ounces) and fired a 9mm bullet from an 8 round magazine.
The Walther-P1 is basically the German Army World War II P38, which was adopted by the post-World War II German army, and some local police departments there. It's an 800 gram (28 ounce) weapon firing 9mm bullets from an 8 round magazine.
There are actually a lot of used police pistols available in the West, as newer and more effective models have been introduced in the last decade or so. But German weapons have always been much admired in Afghanistan, and the Walther-P1 is considered the gold standard when it comes to side arms.