Yellow Jacket® Solar Pile Sleeves help mitigate frost heave on solar panel W piles. Yellow Jacket® is a patented prefabricated pile sleeve that provides a slip plane between the W pile and the soil. The pile sleeves are lightweight, safe, and quickly installed - increasing job productivity. There's no mess and no exposure to potentially dangerous coatings. Yellow Jacket® Pile Sleeves are a product of Foundation Technologies, Inc, a respected leader in the deep foundation industry since 1986. Foundation Technologies, Inc. delivers products and services that make deep foundations better.