The Testo 0638 1742 is an oil pressure probe. The 0638 1742 checks for the oil levels in a compressor. It has a measuring range of 0 to 25 psi rel (0 to 25 bar rel) with an accuracy of 1.5% of full-scale value. The 0638 1742 is compatible with the 556, 560 and 570 Refrigeration System Analyzers. The length of the fixed cable is 9.514 ft (2.9 m).