Cartridge bearings for SJSC hubs

from the SJS site

A high quality Large Flange pair of track hubs, front OLN is 100mm, rear OLN is 120mm but will respace down to 110mm or up to 130mm with the addition or removal of washers. Rear Axle is 10mm in diameter, Front is 9mm, and hollow for lightness. Overall length of the axle is 165mm. The hub can be spaced to 130mm without swapping the axle.
Very good value for money compared to other hubs.Supplied with 2 lockrings.
Replacement bearings. - These are the same bearing for both front and rear. Our part no. is 17093.

So yeah front bearings are usable in the rear.