Manifold Gauge Set (also called a Testing Manifold or HVAC Manifold Gauge).
It’s a standard tool used by refrigeration and air conditioning technicians for:
• Testing system pressures (low side/blue gauge and high side/red gauge)
• Charging refrigerant into the system
• Evacuating (pulling a vacuum) to remove air and moisture before charging
• Recovering refrigerant, checking for leaks, etc.