TLS Laboratories has developed 3 product families that are distributed nationwide:
Corner Flash GS series- Especially designed for recessed window openings. These accept a slope at the lower edge of the recessed opening.
Lightning Flash Flashing Corners- Especially designed for window pans and other transitional flashing needs. Electrical outlets and open nail fin corner problems are easily solved with Lightning Flash!
GS Flex Corners- These are heavy duty corners for heavy duty applications. These work well for recessed openings that do not have a slope at the lower edge. They work great for window and door pans.