Your pH Intellical PHC301 sensor kit comes with 4-7-10 Singlet calibration buffers reagents and standard Renovo N cleaning solutions to provide an all-in-one easy to use reliable solution for your pH electrode calibrations and maintenance, helping you to ensure accurate pH readings with your pH Meter. Ideal for on-site analyses, sealed pouches are easy to transport with no risk of spillage. Each Singlet pouch provides fresh and reliable buffer preventing contamination and air exposure, just open the pouch and insert the electrode. Pack of 20 pouches for each pH buffer allows more than 4 months of pH electrode calibration when calibrating once per week, or 20 calibrations at a very attractive price compared to if purchased separately.