The RE 10 Range Extender is a useful accessory for testing high conductivityppm solutions beyond the normal range of your DS meter except 512T10 Inserting the RE10 into a sample filled cell cup increases the maximum range ten times Use the Range Extender whenever the reading is off the scale Additional Details ------------------------------ Product description: Keep your Myron L meter and system running smoothly and accurately with these parts and accessories. The RE-10 range extender is ideal for testing high conductivity/ppm solutions beyond the normal range of your meter. To use, simply fill the cell cup with your sample and push the range extender into the cup, seating the o-ring seal. Use and read your DS meter as normal, multiplying the reading by 10. Once done, remove the range extender from the sample cup and rinse the cup and extender with distilled or deionized water to eliminate salt buildup. Do not use the range extender with model 512T10.