Designed to install a new cable or innerduct into an existing occupied 1-1/4 in., 1-1/2 in. and 2 in. innerduct (subject to space being available). The Single Size Junction Box comprises an aluminium base and lid that form a pressurized air chamber into which one end of an existing occupied innderDuct can be attached. The existing cable can exit the box through an opening that has three cable seal slots, one of which will house the seal to suit the size of the existing cable. The third branch is then connected to a Cable Blowing Machine via a short slave length of innerduct for the installation of the extra cable or tube(s). A collection of seals ranging from 7.5 – 20 mm are included with junction box.