When sourcing acoustic diffusers, you must prioritize the Effective Diffusion Frequency Range. For instance, a QRD (Quadratic Residue Diffuser) should have a well-defined well depth and width to target specific frequencies, typically ranging from 400Hz to 4000Hz. Additionally, verify the Material Density; high-density solid woods like Oak or Walnut provide better reflection energy than lightweight foams. For commercial projects, ensure the product meets Class A Fire Rating (ASTM E84 or EN 13501-1) to comply with building safety codes.