A Type-IV phaser was a type of phaser emitter usually installed on small Federation Starfleet spacecraft.
History[]
In the 2360s, Federation shuttlecraft classes such as the Type-15 and Type-16 shuttlepods routinely carried two emitters of this type. Additionally, Type-6 and Type-8 shuttlecraft, while both normally unarmed, could be fitted with up to two emitters of this type for special missions. (TNG reference: Star Trek: The Next Generation Technical Manual, ST website: StarTrek.com)
In the 2370s, Type-11 shuttlecraft were fitted with emitters of this type. (TTN novel: Synthesis)