Who is going to use it?
Just the children, and their friends? Don't forget older brothers & sisters or older members of your extended family. Will it be used by adults?What are the users' expectations?

Is it to be just a bouncy play area for several children at once or is it for more sporting use by one at a time, i.e a young gymnast ?Is it to be used by a child who trampolines as a sport?

Even if your trampolining child is only 9 or 10 years old and quite light, you could possibly get away with buying a Prince 18 but do be aware that the 56 x 7 inch springs will be expected to do much the same job as 100 or more 10.5 inch springs down at the sports hall. Inevitably some of them will break.

Round versus Rectangular
If you want performance and serious airtime always choose rectangular. Proper trampolines in sports halls have always been rectangular because all the springs work at a different rate to give a quicker response and a more powerful lift. For this reason we strongly recommend only one user at a time on a rectangular trampoline.

On a round trampoline all the springs work at the same rate. Thus the larger the trampoline the softer, slower and less high is the bounce. Very safe though and ideal for multiple use, messing about generally pushing your luck.

A Black Polymesh or 2-String bed?
As in so many cases there is a trade off between performance and comfort.
The 2-string bed being nylon and allowing a good through flow of air will get you bouncing higher. It will dry out quicker after rain. But it has a slightly rougher surface and may cause "mat burns" i.e grazes to elbows and knees.
You should also be aware that swimming pool chlorine will shorten the life of your 2-string bed.
The black mesh bed being polypropylene with absolutely no extra elasticity and giving a poor through flow of air will give you less lift. But its smooth surface will never graze even the tenderest of skin.

Weight & Age limitation

Although we give you simple weight & age limits for each model you must also consider experience, strength & skill too. The greater the height attained by the bouncer, the bigger the loading on the trampoline springs. So whilst someone may be technically under the maximum recommended weight for a particular trampoline, if they are very competent & fit, they could manage to overload the springs. If in doubt always buy bigger, you will not regret it.