Question about TFA PH Check

For the storage you need a KCl 3 mol solution, I got it from the pharmacy. For calibration I took pH 4 and pH 7 by Mettler Toledo, expensive, check for other providers.

Thanks! I really suggest that - along with this product - Galaxus should offer necessary items for storage & buffer solutions to calibrate why not from Dostmann (manufacturer) or other “not so expensive options”. Its absurdly time wasting finding necessary items to operate and finally get to measure PH