Fluke 50 Series Thermometers include: Fluke 50S, 50D, 51, and 52 Thermometers. This will also apply to The general style is the same on all Fluke 70 Series, and Fluke 70 Series II Multimeters including the following: Fluke 21, 21 Series II, 23, 23 Series II, 25, 29, 29 Series II, 70, 70 III, 73, 73 Series II, 75, 77, 78, and 79.