The connection rubbers on the top and bottom of each MAP sensor tube can be the source of really rough running of your bike's idle and small throttle positions. Even the slightest air leak will cause these problems and over time the original rubbers can rot or become loose on the inlet manifolds.
These replacement rubbers are made from black silicone, have a nice tight fit and make replacement much more economical than buying a pair of complete MAP tube assemblies from Triumph. It's worth keeping these in your toolbox as spares, just in case.