Burlington Traditional 540mm Inset Basin - 1 & 2THIllustrated Code B13 1THB13 1TH: Fully inset vanity basin 54cm 1TH B13 2THB13 2TH: Fully inset vanity basin 54cm 2TH Additional Information The overflow is to solve the issue of a dripping tap if the plug is left in. It is not designed to take a flowing tap. To order the correct tap hole (TH) configuration simply use 1TH or 2TH at the end of the basin product code. Guarantee 25 years domestic installations 1 year commercial installationsStandards