gee u didnt have to pay that much 4 a collar but at least u have peace of mind its a real good one. the grub screws go on the counterbalancers of the crank. std cranks have aluminium bungs which can apparently come loose with high hp/rpm. so a machine shop removes these cuts a thread and grub screws them. also the crank can then be flushed out properly through the journals.
edit, but then your crank collar has to be grub screwed also this is seperate