This set of TO-92 transistors includes four different types: BC547, BC557, 2N3904, and 2N3906. They are all NPN transistors with a TO-92 package/case. These transistors are commonly used in a variety of electronic projects and can be a great addition to your collection. With their small size, they are ideal for compact designs and can be easily integrated into your circuit board. Purchase this set today to enhance your electronic components collection!