4 lb Board is manufactured from felted mineral wool bonded together with a high temperature binder.  It is a very efficient, semi-rigid type of insulation recommended for commercial and industrial applications from -20 degrees farenheit to 850- dgrees farenheit.  There is a wide range of applications for the Mineral Wool Board including use on building envelopes (accoustical & wall), bag houses and precipitators, ducts, storage tanks and equipment.  It is easily cut with a knife, fit snugly over irregular surfaces and applied quickly becouse of its light weight.  Generally, attachment is by means of weld pins and clips, or wire mesh, and then finished with either metal, plastic lagging, or reinforced mastic