For Engine Blocks (Cylinders & Decks)
One probe is usually good for use on both Cast Aluminum and Cast Iron Engine Blocks. The 2 inch radius allows the probe to measure the concave surface inside cylinders. The radius is gentle enough that the same probe can also be used to measure on the flat surfaces "decks" on the block. This one probe will work for over 90% of Cast Aluminum or Cast Iron Blocks.
T-104-2120
> 0.500"/5MHz with 2 inch radius
> this is the standard probe supplied with PR-82
++ In instances where the above probe does not work, or if the block is made from a very old Aluminum Cast Aluminum, an alternate probe should be specified p/n T-104-4120 (0.500"-10MHz), also supplied with a 2" radius.
For Heads (Ports)
Probe selection depends upon type of material; cast iron or cast aluminum. This probe has a 0.55" radius and is supplied with either a 1 inch wand or 9 inch wand, depending upon user preference.
Cast Iron
> 0.250"/5MHz with 0.55" Radius
with 1 inch wand T-162-2110
with 9 inch wand T-132-2110
Cast Aluminum
> 0.250/10MHz with 0.55" Radius
with 1 inch wand T-162-4110
with 9 inch wand T-132-4110
For Chassis Tubing
This would be used by chassis builders as well as sanctioning bodies (i.e. NHRA, ARCA, etc.). One probe is normally suitable for any application, assuming they do not want "thru-paint" capability.
T-101-4000
> 3/16"-10MHz flat bottom (no radius)
For "thru-paint" capability, when measuring chassis tubing for use with the PR8V
T-102-2700
>0.250/5MHz Hi-Damp for use in MMX Mode | 
Features
Standard Range: 0.040 to 6.00 in / 1.00 to 150.00 mm
Simple operator controls virtually eliminate training
Used to create an ultrasonic coupling between the probe and material to be measured
