The Stage 805-STR44xxx is a low cost, rack and pinion, stepper motor stage that offers 4" x 4" of travel in a thin (19mm thick) X, Y stage.
The Stage 805-STB44xxx is a premium quality, ballscrew, stepper motor stage that offers 4" x 4" of travel in a thin (34mm thick) X, Y stage.
The stage 805-STM44xxx is a low cost manual stage, that offers 4" x 4" of travel in a thin (25mm thick) stage.