Shop our large selection of balloon parts and accessories to ensure you have everything you need for your balloon clusters. WHA Dura Bonker balloons have a screw on bottom to connect to the stem as opposed to a 'snap-on stem' of other similar balloon type systems. An easy way to identify if you have the correct hardware for Dura-Bonker Replacement Balloons is the plastic cup that cradles the bottom of the balloon should be clear in color and NOT black.