had a trip to ikea and had a look at the shelfs to fit in the kallax shelving, i could have got just a glass shelf that fitted in but i would have had to mess about measuring and drilling my own holes to fit this and get it level, i decided to get the insert that you build up this comes with holes already drilled for the shelf but the main reason i went for this is that it has a back to it and comes with a glass door so should help to keep the dust down.
the screws that hold the hinges in place also screw into the shelving holding it all in place so things cant fall out of the back unlike they could with just a shelf, two screws go into the opposite side to help secure it all, the glass door can be put on to open from either side.