Our revolutionary insulating gasket seal prevents heat loss where the two cover halves fold together.  When the cover is shut, the two halves seal automatically which is critical to long-term energy savings. Payback on energy savings is typically seen in less than 12 months, according to independent testing. The GHSG™ also protects the bottom of the cover from abrasion. The Heat Seal Gasket design is another example of Sunstar innovation. (optional on all hinged covers).