After testing the Nano Hertz Sauna Vest for 3 weeks, I’m both impressed and slightly conflicted. Here’s the real tea:

🔥 HEAT TRAPPING PROS: The polyurethane lining WORKS. My HIIT sessions felt like hot yoga – sweat pooled instantly. One wearer noted it made winter workouts feel like a sauna, and I agree. VO2 max improvement? Noticeable during sprints.

⚠️ FIT ISSUES: Size chaos alert! As a 5’7” 160lb user, the XL fit like a sausage casing (per another reviewer’s complaint). But a 36DD wearer loved the XL’s snugness. Moral: Size down if between sizes. The "Danny DeVito torso" comment? Sadly accurate – it rides up on longer torsos.

💦 SWEAT PERFORMANCE: Unlike cheap PVC suits, this breathes while trapping heat. A Spanish reviewer raved about sweating buckets during walks. But beware – one user reported slippage when drenched, though I didn’t experience this.

🎯 BODY SHAPING: Instant waist cinching! The compression flattened my post-lunch bloat convincingly. However, the armholes dig in on broader frames (per a 180lb user’s gripe).

VERDICT: 4/5 stars. Fantastic for short-torsoed users wanting thermogenic boosts, but quality control needs work. Pair with electrolyte drinks – you’ll need them!