The tube is 300mm long and has a massive bore of 25mm. Most of your typical snorkeling snorks are a bit longer for wavy sea conditions and splash ? but for pool sport use you want something more compact that doesn?t waggle about or get stuck in peoples armpits. In fact, we still recommend cutting off a few extra centimetres (to personal preference). So with the shorter length and wider girth you are pushing out a similar volume of water as a ?normal? snork but you suck in air much faster (dilated aperture improves laminar flow due to an improved surface area to volume ratio) so it takes less effort to take those desperate breaths after a sprint and recover so you can get back on the bottom of the pool quicker.