These new steel tipped probes are epoxy sealed to increase water resistance.  The steel tip also transfers temperature change faster which can be beneficial in setups where the probe is monitoring air temp like incubators.  12ft length.
 
This style temperature probe will work with:
 
Herpstat Intro+
Herpstat 1 Basic
Herpstat 1
Herpstat 2
Herpstat 4
Herpstat 6 
Herpstat 1 SpyderWeb
Herpstat 2 SpyderWeb
Also works with the following discontinued models:
Herpstat ND
Herpstat II
Herpstat Pro
Herpstat HP
Herpstat EZ1 and EZ2
Herpstat Intro
Any Redline model
 
Original model Herpstats (front of unit is green and serial number starts with 5010xxxx) with a serial number between 50101000 and 50102600 require an older style probe that is no longer available.