Waterproof Temperature Indicator with Stainless Steel Penetration Probe. The TM25 is a Compact Waterproof Temperature Indicator with Stainless Steel Penetration Probe. Includes 4.1" (105mm) stainless steel penetration probe with 5ft (1.5m) cable. Measures temperature from -40°F to 392°F (-40°C to 200°C).