TSA Precheck

Active TWIC® and HME holders can use their credentials to obtain TSA PreCheck™ | Transportation Security Administration

Tells you right in the link.

TWIC® and HME holders can obtain TSA PreCheck expedited screening by entering the identification numbers printed on their TWIC® card or state-issued CDL during the airline reservation process. Active TWIC® card holders enter their TWIC® credential identification number (CIN) in the known traveler number (KTN) field of their airline reservation. The CIN is printed on the back of each TWIC® card in the lower left-hand corner. Active HME holders enter the two-letter state abbreviation and CDL identification number from their state-issued commercial driver’s license in the appropriate KTN field. (For example: NY12345678.)

 

Not sure about TWIC

NEXUS cards have extra digits after the number, on mine it has SC945 after the 9 digit number. There's also another 9 digit number that's not labeled. Not sure what that one's for