Cheap models heat for 2 minutes then cut off for safety-theatre. Good ones (like our #1) hold ~104F for the full 15-min session. If you buy for stiffness, heat matters more than vibration count.
Claimed 6 hrs often means 3 in real kneading mode. We drain each unit at level 2 until dead — pick anything over 4 real hours or you will charge every other day.
Over 550g slides off; over 45dB annoys coworkers. Our winners sit 320-480g and stay under 40dB. Try level 1 for 10 min first, then go deeper.
