A concentrated bottle of weedkiller; for the same price as a regular 1L bottle you can get this, which makes 14L (which would have cost over £50!). Put another way, make a litre of this stuff for only 29p. Amazon currently has the concentrated weedkiller in 4 sizes, but this hits the sweet-spot for being far cheaper than any other sized bottle, at ~75% RRP. Camelcamelcamel indicates this is the lowest price yet. Fill your (gardening) boots.