Material: stainless steel, this product is very durable and can easily create perfect external and internal corners. External/internal corner cutter. Best tool for drywall corners. Material: stainless steel. Internal corner cutter, 40.8 cm x 14.5 cm. External corner cutter, 40.8 cm x 14.5 cm. When adhesive is applied to the drywall, it can be bent to a perfect 90-degree angle. With this two-piece internal and external corner cutter, you create a smooth, polished surface on both internal and external corners. You can use it with various types of plaster, such as drywall, stucco, and concrete. When applying adhesive to corners, the internal corner cutter makes it easy to achieve a perfect 90-degree external corner. The external corner cutter makes it easy to achieve a perfect 90-degree internal corner. 90 degrees when applying spackle around grooves. The two-piece set of internal and external corner cutters meets your various application requirements, making your plastering work easier and more efficient.