Gas treatment apparatus

Apparatus for treating an exhaust gas from an internal combustion engine comprises a tubular compartment (102) containing a treatment member (110), the compartment comprising a tubular canister (42) and a retainer (36), the tubular canister having stopping means (46); the retainer being releasably attached to the canister by axial clamping means (24) such that the treatment member is secured in place though contact at one end with the stopping means and at the other with the retainer. Preferably, the retainer and canister have outwardly projecting flanges (34, 40), which may be circumferential, on which the clamping means (preferably a v-clamp) can act. The retainer may also include an inwardly projecting flange (38) that makes contact with a second end of the canister. The treatment element is preferably a particulate filter and the canister and retainer made from stainless steel.