Sontaran blasters were a form of energy weapon.
The blasters were used to great effect in the Sontaran invasion of Earth in 2009 and proved a great weapon against UNIT. They fired a red energy burst that could kill a human with a single direct hit without leaving any signs of exterior damage. Despite being known as "lasers", the bolts travelled slower than light. (DW: The Sontaran Strategem / The Poison Sky)
Commander Kaagh carried a more compact version of the blaster with the same ultimate design. However its bolts were thicker and caused more damage. Kaagh was forced to give it up to Sarah Jane Smith after his defeat on Earth. It now lies in her attic. (SJA: The Last Sontaran)
Stike, Varl, and Turner were all carrying large rifles at one time. These may be one and the same with the Sontaran Blasters.