Note: 84-IP can be generally used in lab. 84-IIP is the accessory electrode for pH meter model P-IA and PX-IA. It has a special direct BNC plug to be connected to pH meter. These three models are acceossories for Pocket pH meter PH serie. 87-IP is for PH-I. It has a special direct plug for connection. It is smaller in size so that it can be temperarily stored in the body of PH-I 87-IIP is for PH-II, can also be generally used in lab. 87-IIIP is for PH-III, can also be generally used in lab. Model : 84-IP 84-IIP 87-IP 87-IIP 87-IIIP Measuring Range: 0 - 14 pH Temperature Range: 0 - 60癈 Zero point value: 7 +/- 1 pH Junction: Ceramic Reference: Cell Ag/Agcl, KCL gel Size: dia.10 x length 120 mm ,dia.10 x length 120 mm, dia.12 x length 85 mm ,dia.12 x length120 mm ,dia.12 x length 90mm Plug : BNC + 1 m cable, BNC ,Special direct plug ,BNC ,BNC + 1 m cable