Ltpgtthis contour 100mm dc extract fan from xpelair is a three speed fan operated by an integral overrun timer which is adjustable between thirty seconds and thirty minutes time to be set at installation this stylish and efficient fan incorporates a trickle option which means it can be used as part of a whole house dmev systemltpgt ltpgtthe contour cdc100t provides an affordable discreet and highly effective ventilation system suitable for use in almost any domestic environmen