These are to replace the wooden bearing sleeves on the Y axis.
There is a new all aluminum bearing sleeve that PB sells as an upgrade for the LCv2, this is a cheap and nearly as good alternative.
Print the file 4 times for a set of 2 bearing sleeves, the original fastener hardware can be re-used, but i recommend lock nuts and washers over the stock hardware.
PLA - 2 perimeters & 25% infill is plenty strong.
This is sized for 8mm LM8UU Linear Ball Bearings