pizza stone

I'd also suggest:

https://www.amazon.com/dp/B00OXHQL3Q/ref=twister_B00GGMFK9M?_encoding=UTF8&psc=1 save your thermapen money and buy this. It works great for a LOT less money.

https://www.amazon.com/Weber-7203-iGrill-2-Thermometer/dp/B01MG2CNDL/ref=sr_1_3?ie=UTF8&qid=1498510072&sr=8-3&keywords=igrill+2

http://www.kickashbasket.com/store/product-detail.php?product_id=1

https://smokeware.com/products/stainless-steel-vented-chimney-cap