The Broilmaster 12-Inch Double Side Burner Insulated Sleeve (BSASL12) is required when installing the BSABF12N Double Side Burner into a combustible outdoor kitchen island structure — including wood-framed or composite island builds. The double-lined stainless steel sleeve creates the thermal barrier needed between the burner unit and surrounding combustible materials, ensuring safe installation and compliance with clearance requirements. If your island is constructed from non-combustible materials, consult Broilmaster's installation manual and local codes to determine whether the sleeve is required.