Immersion probe, type K, -65 ... +1000 °C

inexpensive, elastic (rigid)
non-corrosive V4A tube Ø 3 mm, L=130 mm, plastic handle, anti-buckling glanding, 1 m silicone cable, miniature flat plug

Response time T₉₀:
water 0.4 m/s <2 s, air 2 m/s approx. 40 s