It basically means there are no seams on the running lengths. The only seams are on the inside and outside of the corners. Seamless gutters are made from aluminium , due to it's lightweight, durable and non corrosive properties. Bridge Rainwater Solutions use on board gutter forming machines in their vans, which allows a roll of aluminium to form a continuing line of guttering which can be up to 40 metres in length. This allows all seamless aluminium guttering to be produced on site, made to measure.