All of our black vitreous flue pipe is heavy duty. It has a very slight sheen (like a vinyl-silk, a cross between matt and gloss).
As with all vitreous pipe the bottom end narrows to a lesser diameter to enable insertion into other pieces of pipe (male is always on top). Key reason is that any condensation that trickles down inside pipe cannot escape. Straight lengths can be cut using a grinder and 115mm cutting disc (available from this online store).