A sandscreen joint is capable of providing zonal isolation. The ends of a portion of the sandscreen are capable of extension on activation of the sandscreen, including transition areas, which are coated with an elastomer sleeve. On activation of the sandscreen, the sleeve is pushed out into contact with the bore wall and serves to isolate the zone on one side of the activated sleeve from the zone on the other side of the sleeve. Thus, the sleeve on the activated sandscreen may prevent fluid from flowing axially along the bore between the bore wall and sandscreen. This may protect the weave at the transition area, preventing axial flow through the transition areas.