This kit is only suitable for the current XTX200 first stages (FSR and FST type). A 5th port offers the user more versatility in terms of hose routings and port positions depending on the type of diving. This particular version incorporates a heat exchanger which acts as an additional safeguard against freezing.
Please be aware that this 5-port kit cannot be used on the old style XTX 1st stages. It has to be one of the current (post-September 2012) XTX200 with the new metallic decal.
5th port allows for a hose routing options that can be advantageous when mounting the first stage to twin cylinders.
Heat exchanger helps resist freezing in cold water.
This kit cannot be retrofitted to any of the old XTX first stages, it can only be fit to new XTX200 first stages which use the metal decal. This is specified in the kit instructions.