Check the listing for details. HM Digital 1000ppm TDS Calibration Solution. Color: natural, Condition: New. Listed at 21.89 USD. HM Digital 1000ppm TDS Calibration Solution Product Image Item Description For optimal performance, re-calibrate your meters periodically or if testing TDS or conductivity levels in wide or different ranges Features For optimal performance, re-calibrate your meters periodically or if testing TDS or conductivity levels in wide or different ranges NaCl calibration solution Comes in lightweight HDPE plastic bottles Laboratory quality NIST-traceable solutions Any brand TDS meter can be calibrated to any brand of calibration solution Bottles have a convenient wide mouth, allowing a user to simply insert the meter into a stable bottle Sealed with coated foam liner Payment We offer secure and easy checkout for all major credit cards through PayPal. Shipping We offer fast and free shipping to the continental United States. We do not offer international shipping at this time. We do not ship to PO Boxes at this time. Returns We offer hassle-free returns within 30 days of the purchase, no questions asked as long as the item is returned in the same condition it was received. Please contact us for a return authorization and for the return shipping address.