The F series strength machine, F90 is one Dual station fitness machine, i.e. training the Prone Leg Curl and Leg Extention on one same machine.designed with convenient, easy-to-adjust ankle pad and shin pad from the seated position. The below-the-knee shin pad design facilitates proper leg curl form. Exercisers can easily engage the add-on weight with a simple push of a lever to increase the work load.