Key specs vary by technology: For Laser Hair Removal, look for triple wavelength (755nm, 808nm, 1064nm) to treat all skin types. For Skin Rejuvenation, ensure the device has a high-quality capacitor for stable pulse delivery. For Body Slimming (Cryolipolysis or EMS), check the number of applicators that can work simultaneously to increase salon turnover. Always confirm the lifespan of consumables, such as the number of shots available in a laser handle (e.g., 20-50 million shots), as this directly impacts your long-term ROI.