Drow Crossbow of Speed (Drow Crossbow of Speed +3 in-game) is an enchanted light crossbow +3 in terms of enchantment. Like all adamantine items, this will turn into Adamantine Dust when it's taken out of the Underdark. This weapon is nearly the same as the Light Crossbow of Speed, but since the mentioned crossbow is a +1 weapon, the drow variant weapon with +3 bonus to damage and -3 THAC0 with a speed factor of 1, is a lot better. But the +1 crossbow isn't made of adamantine and therefore can be used anywhere.