AFRSI blankets replace the vast majority  of the LRSI tiles. AFRSI consists of a low-density fibrous silica batting that  is made up of high-purity silica and 99.8-percent amorphous silica fibers (1 to  2 mils thick). This batting is sandwiched between an outer woven silica  high-temperature fabric and an inner woven glass lower temperature fabric. After  the composite is sewn with silica thread, it has a quiltlike appearance. The  AFRSI blankets are coated with a ceramic collodial silica and high-purity silica  fibers (referred to as C-9) that provide endurance. The AFRSI composite density  is approximately 8 to 9 pounds per cubic foot and varies in thickness from 0.45  to 0.95 inch. The thickness is determined by the heat load the blanket  encounters during entry. The blankets are cut to the planform shape required and  bonded directly to the orbiter by RTV silicon adhesive 0.20 inch thick. The very  thin glue line reduces weight and minimizes the thermal expansion during  temperature changes. The sewn quilted fabric blanket is manufactured by Rockwell  in 3- by 3-foot squares of the proper thickness. The direct application of the  blankets to the orbiter results in weight reduction, improved producibility and  durability, reduced fabrication and installation cost, and reduced installation  schedule time.