Parker 6-4 RB-B Brass Pipe Fitting, Reducing Hex Head Bushing, 3/8" NPT Male X 1/4" NPT Female Hexagonal reducing bushing for connecting pipes of different sizes Female National Pipe Taper (NPT) threads on one end and male NPT threads on the other for connecting different types of pipe Made from brass for higher corrosion resistance than steel NPT thread for creating tighter seals than straight threads More economical than steel