The Quick-Fix is a secondary weapon for the Medic. It is a prototype Medi Gun with a group of three gauges on one side, a (cosmetic) ÜberCharge gauge on the other side, and what appears to be a blender for a body. The main gun is coupled with a medicinal reactor backpack with glowing portions that replaces Medic's default backpack.
The Quick-Fix allows for +40% faster healing and +10% faster Übercharge charge rate. The Ubercharge itself for The Quick-Fix gives the medic and the team mate being healed 300% increased healing and immunity to movement impairing effects (Slow effects and knockback) for the duration of the Übercharge. This at the expense of -50% Overheal on the patient can only overheal a target to 25% extra health. The ubercharge is still 8 seconds long. Despite the ubercharge description saying 300% extra, community testing has found it to be 200% extra. The quick fix is also seen in Meet the medic.