I've tried LED masks for firmness before and didn't see much change. What makes this different?

Most LED devices lose the majority of their power before it reaches the skin - up to 95% of LED light simply bounces off the surface. Laser light behaves differently: because it's coherent, polarised and monochromatic, it stays concentrated and intense rather than scattering at the surface.

That's the structural reason LED can feel warm without visibly firming the skin, while a true Laser is built to deliver a visibly firmer, tighter-looking result.