The R13-203B-01-BR is an SCI part, a self-clinching nut with a blind hole type. It is made of steel and zinc plated for corrosion resistance. It has a M4 thread size with a nominal 6.0mm thread length, a 3.0mm nominally tapped hole depth, a nominal 9.5mm overall length, and a 4.3mm nominal head height. It is used in thin metal sheets for a strong, secure fastening. The blind hole type allows for installation without access to the back side, making it ideal for places where space is a concern.