Lululemon Metal Vent Tech polo shirt.
Stretch poly/nylon in light gray.
Very good condition - no holes, no stains.
Size tag missing - fits approx. snug medium by their typical modern/slim cut sizing but might be small in other standard brands.
Measurements in inches:
pit to pit 19.25
waist 18.5
shoulders 17
sleeves (from shoulder seam) 9
rear length (excluding collar) 28.25