The RAM-B-218-1U has one 1 inch diameter rubber ball and .25 NPT female thread no flange fitting. The balls can connect to any RAM B ball sized accessory.
RAM-B-218-1U shown above.
RAM-B-218-1U Features:
Warranty: Manufacturer's, RAM Mounts (National Products Inc.), Limited Life Time Warranty.
Material: Black powder coated marine grade aluminum.
Ball Size: One 1 inch diameter rubber B sized ball.
NPT Size: 1 inch B ball sized socket and 1/4 inch NPT female thread.
Description: The RAM-B-218-1U connects to any 1/4 inch NPT male thread, including the RAM-PF-585 (RAM-PF-585-6, RAM-PF-585-9, RAM-PF-585-12, etc.) and RAM-PA-xxx NPT series. The single socket can connect to any 1 inch B ball sized accessory.
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: