When evaluating cordless hair clippers, prioritize the motor type and speed; professional models should feature high-torque rotary motors reaching at least 6,000 to 7,000 RPM. The blade material is critical for longevity—look for carbon steel, ceramic, or titanium-coated blades which offer superior heat dissipation and sharpness. Additionally, verify the battery chemistry, ensuring the use of Lithium-ion (Li-ion) batteries that provide at least 120-180 minutes of runtime with a quick-charge function (e.g., 2 hours for a full charge).