MMT Acoustix® set of 3 Pyramid Acoustic Foam, ProStudio Sound Setup, Soundproofing Noise Reduction Acoustic Panels | 2x2Ft 2” Thick, Charcoal

The product description says NRC >0.90 , but does provide the required sound proofing. I installed on all the windows and door in my kids room where my son plays drums. The sound I could hear outside my house is still the same as it was before.

Very very good product....Thank u MMT & Amazon

If you are looking for acoustic panels then the MMT ones are the very best.