4-inch T-shank jigsaw blades are the industry standard for modern power tools, designed to fit 90% of current jigsaw makes and models including Bosch, DEWALT, and Milwaukee. The "T-shank" design features a tang with a notch that allows for tool-less blade changes and provides maximum grip and stability during operation. These blades typically feature a 4-inch overall length with a 3-inch working length, making them ideal for cutting materials up to roughly 1-1/4 inches thick depending on the tooth configuration.