When sourcing foam insulation bricks (also known as lightweight refractory bricks or thermal insulation bricks), you must prioritize Thermal Conductivity, which should ideally be ≤ 0.15-0.40 W/m·k depending on the temperature grade. Bulk Density is another critical factor; for high-efficiency insulation, look for densities between 0.6 to 1.2 g/cm³. Additionally, verify the Cold Crushing Strength (CCS) to ensure the bricks can withstand structural loads, typically requiring ≥ 1.5 MPa for non-load-bearing insulation layers.