We are doing a review on the powerbox which should be out very soon. it will include some video tutorials showing how it works as well. From what I understand the powerboxes are very good but I have no first hand experience with them yet. Only going by what other opinions from flyers I've spoken with or read here. YOu may want to start a thread in the IMAC or Giant forum asking specifically about the PB's or do a search for existing info on our advanced search page