Variable pressure is required and I don''t know of anything that requires 15lbs of pressure. I have a big Presto pressure cooker. Presssure cookers can have either h pressure guage or with the weights that were mentioned at 5-10-15 lbs. Either one requires frequent monitoring of the pressure which can be regulated by the amount of applied heat. Both have their advantages and disadvantages. My cooker will hold 7 quarts and 7 pints all at once IF wide mouth jars are used (they''re just a little shorter). I think I paid about $100 for the cooker. There are some really heavy duty and heavy money cookers available, but the Presto works just fine.