This hardware package comes with the Trekker Chassis. It is all the hardware needed to put the chassis together and mount the OOPic-R and OOPic-R Expansion board. The chassis comes with one hardware package (either for the OOPic II of OOPic-R). If you purchased your Trekker Chassis with the OOPic-R Hardware and want to change to then OOPic II or if you just want some additional hardware then this item is for you. For a list of the items follow this link.