Mill-mixed perlite-aggregate gypsum plaster, just add water at jobsite (3 to 3.75 gallon per 50 lb. bag). Lightest-weight and highly insulated plaster. Conforms to various designs and achieves durability in walls and ceilings. Can be applied by hand or machine methods, on gypsum or metal lath, clay tile, concrete, or cinder blocks. 50 lb. bag.