The model is for one side only for a whole board please duplicate and flip one of the two.
It's designed to taper off at the rear and tops to create better clearance on the rear truck as I noticed with the original bash guard as well as earlier versions of this that the motor cable holders can actually touch the bash guard at large lean angles hence this design has a cutout and is flat on top.
I would recommend printing this in a more durable and non-brittle filament, personally I'm using eSun PLA-ST, and have tried ABS as well as standard PLA and found the first to be too brittle and delaminating upon impacts and PLA to just shatter after a while, whilst PLA-ST has been just scratching.
The author marked this model as their own original creation.