VELUX ZCT 100 Extension section for ZCT 200K - 100mm VELUX Sale! from £30.00 £30.00 (inc VAT) £25.00 (ex VAT) Qty. Add to Basket This item is currently on backorder but you can still purchase it now and we'll ship as soon as more become available. Description: The VELUX ZCT 100 extension section has been designed to give an additional 100 cm length to the ZCT 200K. Offers a combined, total length of 2.8 mtrs.