A Full Roll of Solid Weeping Tile (Non-Perforated pipe) is 4"x 100' (4" x 30.48m)
 
By the Metre:
When increasing the quantity of By the Metre your length of Membrane will grow.
I.e. Quantity 1 = 1 Metre, Quantity 2 = 2 Metres, Quantity 3 = 3 Metres, etc.