There are two operating systems used on D25LT sensors - WIN 98 (Generation 1 or GEN1), and WIN XP (Generation 2 or GEN 2.
D25LT GEN1 use a Dymo Label Writer 400 or Turbo 400 with the printer driver pre-installed. USB cable plugs in the back.
D25LT GEN2 use a Dymo Label Writer 450 or Turbo 450 with the printer driver pre-installed. USB cable can be plugged into either of the USB ports on the front or the one in the back.