Reddiseals Trickle Vents are supplied in packs and include vent and canopy, or vent, canopy and grill. Surface mounted or flush fit styles are available. All our Trickle Vents comply with part F of the building regulations for new build and replacement. We offer a slim line vent for sash windows. We are proud to introduce the new Link Vent Trickle Vent, which meets the requirements in the building regulations for newly installed windows.