Demer wing tips?

I have heard some great things about slow flight performance from the
Demer tips but can't seem to find who makes them and from where I might
be able to purchase them....

Plan on using them on SuperCub wings on my Sportsman 2+2... Can anyone
supply a link or other information as to where they may be available...

also..

doesanyone have experience with an alternative tip that might work well
with an extended PA22 with SuperCub wings.. Strictly looking for
performance and not at all so much appearance..

Thanks TJ..

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