The HydraFlex Tube uses a 6mm / 1/4in drinking tube and HydraPak Plug-N-Play connection. Check that your reservoir uses a compatible Plug-N-Play connection before replacing the existing hose.
The 91.4cm / 36in length allows the tube to be routed from the reservoir compartment towards the shoulder strap area of a compatible running pack. Route the tube without sharp bends or unnecessary excess movement.
For an insulated drinking tube, the HydraPak HydraFusion Tube is the alternative where reducing heat transfer through the hose is useful.