The HP 65W blue tip charger (commonly used with HP Pavilion, Envy, EliteBook, and ProBook series laptops) typically has the following specifications:
General Specifications
Power Output: 65 Watts
Output Voltage: 19.5 Volts
Output Current: 3.33 Amps
Input Voltage: 100-240V AC (worldwide compatible)
Input Frequency: 50–60 Hz
Power Connector Tip:
Blue pin (Smart Tip / Smart Blue Tip)
Outer Diameter: 4.5 mm
Inner Pin: 3.0 mm with a center pin (smart sensing pin)
This is often referred to as the 4.5mm x 3.0mm connector.