From Halopedia, the Halo wiki
Anatomy and physiology
The Gasgira are diminutive, large-headed creatures that share a number of physiological traits with the Xalanyn. They have six limbs, with two arms and four legs. Their hands are tridactyl (three-fingered), and all four of their feet bear one large toe at the front and a smaller toe at the ankle. Much like the Xalanyn, their feet bend backward in a hyperextended position that hinders terrestrial locomotion, so they make use of thruster "wings" for flight. They wear armor on their torso, head and "wings", red or white depending on rank. Though most of their features are concealed by their armor, the undersides of their helmets reveal a superficially Xalanyn-like oral anatomy, and the exposed skin of their hands, feet and neck exhibit a bluish tone similar to the Harbinger's.
The Skimmers make use of weapons from any faction, carrying them from the hip as the weapon hangs below them. They primarily use the Shock rifle as well as VK78 Commandos and M41 SPNKRs. All ranks throw Dynamo grenades. They have weak spots on their head and thrusters/wings. If killed by shooting a their wings, they explode in a burst of Hard light.
List of appearances