The RAM-B-218-1U consists of a 1" ball and 0.25" NPT female thread. This part connects to any 0.25" NPT male thread, including RAM-PF-585-X flex arm series mounts and RAM-PA54XX rigid arm series mounts.
NPT Thread and Pipe Sizing: NPT (National Pipe Thread) is a standard used in joining pipes and fittings that have a tapered thread. As a general rule, the NPT inch size is the inside diameter of the threaded pipe and is known as the NPS (Nominal Pipe Size). The outer diameter (OD) of the pipe is shown in the table below:
NPT Size (NPS)
Pipe Outer Dia. (OD)
Threads per inch
Powder Coated Marine Grade Aluminum
Ball Size: 1" Rubber Ball "B" Size
Note: The "U" in the part number reflects product packaged in poly bag.