The most often used size of Snap on type is 20mm. It means the inner diameter of closure is 20mm.
Snap on closure can be applied on both plastic and glass bottles only if the bottle neck has a flat and horizontal circle.
A point necessary to be careful is the height of the circle at the bottle neck is different for bottles from different suppliers. It means one snap on closure can not fit all bottles although all snap on closures look almost same. Therefore, different dimensions inside the snap on closures is necessary to fit different bottles. A rough way to check if the bottle and closure are fitted or not is that the height of the bottle neck’s circle should 0.5mm to 0.8mm longer than the distance from gasket to the snap line of the closure. However, the actual situation is more complicated. Therefore, it is very necessary that real bottle samples are checked physcially at the sprayer factory to assure the most suitable snap on closure will be used.
Additionally, unlike screw on closure, back-screwing will not happen when capped with snap on closure, though the requirement of fitting closure with bottle neck size is higher for snap on than screw on.
There is misunderstanding the snap on closure can not be taken down from bottle after it is capped. Actually, it is can be reopened but reopening is difficult, so snap on can be regarded as “non-reopened”.
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