They can be used as Tornado couplings to join bottles neck to
neck when making larger rockets.
The tubes come individually wrapped in a variety
As standard they come with 9.5mm hole, but can
be widened up to 18mm.
NOTE: They do not have a very good sealing surface inside and sometimes require to be tightened significantly in
order to achieve a good seal. If these couplings are
over-tightened they will crack and need to be discarded.
To seal them without over-tightening them, a pair of rubber washers can be inserted
against the sealing surfaces.
They come with a 9.5mm hole, but this can be widened to 18mm
for better airflow and fitting launch tubes through them.
These have been pressure tested to 270psi without
breaking. See experiment: