The VAST-xxt Scanning Sensor comes in three versions:

• TL3 is by far the most common and is suited for most CMM applications.
• TL1 springs are less stiff so can be better for measuring soft parts like plastic (a more gentle probing force).
• TL4 is quite rare but has a stiff spring inside which lends itself to longer styli possibilities.

Each has its own optimum stylus lengths and allowable weights (threshold):

Weight: In the weight of the stylus system you must also take careful account of the threshold values, since otherwise

 there may be a malfunction of the XXT probe head.

Length: The grey area is permitted; the light-blue area is also possible, with limitations in the dynamics of the measuring machine.  The white area is not permitted. The TL3 is by far the most common VAST-xxt version and is appropriate for most measurement applications.

The adapter plates are different for each so customers should take care to purchase the correct ones.

The TL# is stamped on the side of the actual VAST-xxt sensor.  CRM is also a very good source of this information.