Carbine is a compound found on Earth Two.
Zoom showed to be able to pass through the compound with extreme ease, and then proceeded to pummel Barry, and then sped off. With the encouragement of a normal guy, Barry was able to finally phase out of the chamber.
After stealing Barry's speed, and thereby curing himself and amplifying his speed even more, Zoom abducted Caitlin and took her to his lair. There, she met Killer Frost, who Zoom trapped in a carbine chamber. But by working together, they were able to destroy the chamber.
Carbine is a unique compound, that can't be phased through by speedsters easily, and Killer Frost's powers didn't affect it. However, Zoom showed that he can easily pass through it, due to his speed having been tremendously boosted by the Velocity serum.