O-Ring for Total Energy Probe, 6 mm
Outer Diameter: 6 mm, Inner Diameter: 3 mm, Thickness: 1.5 mm, Buna-N, black, Durometer hardness: A70,

Used with esa-systems 6 mm ST probes and UN and SUN probe mounts

The price at right is for each ring. Two are used on most TE probes. 

O-rings are included with the TE probes and mounts.  I am listing these here so that you will know you can get more if you ever need them.

Procedure for replacing O-rings in adapter types UN and SUN