The price for 5 Litres makes this very economical & cost effective solution for developing B&W photographic paper producing excellent consistant results.
It works out a much better deal than buying one Litre of the same product.
Keep it cool & once opened purge the air out of the space with an "Inert Gas" to prevent "Oxidisation" which greatly reduces it's life by many months, quality "Propane" will also purge out any air & do the same job.
Do not use "Co2" as this is not inert & is absorbed by liquids contaminating them.
Depending on how much photo developing you do may make it seem expensive only it can be shared with friends with similar interests.
Excellent developer for RC or Fibre papers. Working solution keeps for longer then expected so you don't need to chuck it away after a darkroom session (within reason).