Hello Petro7, The way the material is covered closely resembles how In-House Solutions delivers their Training Tutorials. You can expect the same quality that is entailed in the print books to translate to the online material. The eCourses do not expire, so once you complete it, you can "re-take" the course whenever you would like. On top of this, you will receive a Certificate of Completion indicating that you have gone through all the material. With that being said, Individuals enjoy purchasing the Mill Level 1 eCourse to review 2D machining and obtaining a certificate indicating completion. If you feel as though you have a strong 2D base, I would recommend purchasing the Mill Level 3 course. If you have any specific questions pertaining to the material, you can give us a call at In-House Solutions!