These come with the pool as part of the package and will be what the manufacturer recommends for that size pool.
Something to look out for though is the size of the skimmer basket. It should be at least 15cm edge to edge and at least 10cm deep.
All in ground pool Skimmer Boxes should come with a vacuum plate so that you can connect a vacuum hose to your skimmer box. This is essentially a plate that sits just above the skimmer basket and has a hole that the hose will fit into.
If you have a choice of skimmer box however you should upgrade to the largest one possible. One of the biggest problems with above ground pools is that the skimmer box is too small. This is because the manufacturers are trying to cut the costs down on the pool but it really is worth the extra money. It will save you emptying the skimmer basket every day!
The pool jets are fairly standard but it is best to have one jet for every 1 HP (horse power). If you have a 1 HP pump output pump or less than 1 jet is adequate. If your pump is between 1 HP and 2 HP then 2 jets would be best. If your filter pressure is at or above 80KPA at startup than you either need to add another jet or take out one of the eyeballs to release the backpressure from the pump."