The material is very thin and generates no heat at all. I understand this is not a sweatshirt, but the material could be thicker, like a Hanes sweatshirt for example.
Ultimate Comfort and Style: Minus33 Merino Wool Ticonderoga Lightweight Men's Clothing, T-Shirts & Tanks
43 Review
Carhartt Workwear XXXXX-Large Men's T-Shirt β Original Clothing for T-Shirts & Tanks
34 Review
AM Fitted T Shirt 3 Pack for Men's Clothing - T-Shirts & Tanks
46 Review
Men's XXL Super T Mockneck π from Lands End - Clothing, T-Shirts & Tanks
32 Review