Black Square Gutter & Downpipe Fittings Menu Options Squareline fittings manufactured by Freeflow. Colour: Black. Profile: Square. Suitable for: Square 114mm gutter and 65mm downpipes. Compatible with most major manufactures please see picture chart. Manufactured with UV resistant materials and covered by a BSI Kitemark - no. KM501316. Available in other colours and profiles. For other rain water guttering systems please visit our shop.