Hello CS list, l know l can make cs myself and l have all the instructions 
but my husband would rather we buy a cs generator with a calibrator(sp?) so 
we get consistent ppms on the cs we make. If anyone knows the best available 
as far as accuracy of ppm produced, and quality of cs and value, please 
advise us if you have personal experience with any particular brands. Please 
advise with the web address and your personal testimony if possible. l need 
to make a purchase right away as we are out of cs! and l hate to not have 
some around the house. Thankyou in advance, sincerely teri.