The FW-5050 is an insulated, fire rated access door approved for use in walls and ceilings. For walls, this door has an Underwriters Laboratories (UL and ULC), 1-1/2 hour "B" label, with a maximum temperature rise of 250 degrees after 30 minutes. This door should be used in walls when temperature rise or heat transmission is a factor. For fire rated ceilings, this door has been approved by Warnock Hersey International for 3 hours (max. size to 24" x 36")