Its a light not a blanket so thickness an warmth are a confusing review item. Having said that I can say great product, it feels like it looks as in not flimsy. The batteries are easily installed. Switching it on for the first time you can see why the glasses are included, its bright! Wearing the glasses is recommended and does help you see reactions to the uv light. Any thing reacting appears slightly different with them on in a good way, white appears brighter white instead of a purple white. Worth the investment in this over others. For technical minded, if a led blows you should be able to replace it easily as they are all on one pcb accessible by unscrewing the front.