Dupla products questions

        Well I finally located a source for Dupla products.  Little boxes
or 7.98 and big boxes for 19.95.  Thing is they have diffrent letters on them
like K.  Unfortunatly my reading ability in German is about equal to my 
reading ability in sanscrif.  So someone who uses the stuff please help me.
Which product do I purchase for what purpose?  How much of it should I use
        Another intreasting thing same store also had SandPoint CO2 injection
systems for $398.00 and Dupla's for $329.00.  They also claim they will be
getting more types in that should market around $200.00.  Is there any
advantage to the higher priced SandPoint system worth the extra money?  And
what makes both of these systems so expensive?  The automatic metering?


I don't write often but when i do watch out.