SMACO Scuba Tank Diving Gear for Diver Mini Scuba Tank Oxygen Cylinder with 15-20 Minutes Capability Diving Oxygen Underwater Breathing Device 1L Diving & Snorkeling Equipment

I'm a professional scuba diving instructor. A full (200 bar) 1L cylinder (200 litres) will give you about 50 breaths on the surface if you breath like a typical adult at rest. The sounds like a lot but you need to half that at 10 metres depth (as pressure increases volume decreases) and even less deeper than that. You also won't be at rest underwater so your breathing rate will increase. You'll be tempted to hold your breath underwater to conserve air. NEVER do this underwater when brething compressed air or your lungs will explode (literally) as you come up and the compressed air in your lungs expands. Forget the claims of 20 minutes - if you get 2 minutes you'll be lucky. Most likely you'll run out of air and have to bolt to the surface or drown, risking lung injury. If you want to scuba dive go on a proper course and learn what to do - NEVER, I repeat NEVER give something like this to your kids. It could literally kill them.

Firstly, Extracting pure ‘Oxygen’ from air is an expensive process which is not achieved with a hand pump!Secondly, Scuba divers do not use 'Oxygen' cylinders except in cases of emergency at the surface. Instead, they use 'Compressed Air.' This is ordinary air found above ground level anywhere in the world which is then compressed (with the use of an expensive 'Compressor') into the diving cylinder at great pressure. In simplistic terms, that compressed air is then eked out little at a time, to the diver throughout the length of the dive.Leaving aside all other issues I will explain the maths. The air we breathe is made up of 21% Oxygen which, when breathed at depths of over 85 metres (approx 275 feet) turns toxic (i.e. poisonous!) and will kill. BUT!, if those same diving cylinders were filled with 100% Oxygen it turns toxic at depths of just 10 metres (33 feet!) as any competent diving instructor will explain.One customer elsewhere asked if this is all the equipment his children need for scuba diving in their swimming pool. I wonder if he’s now checking the depth!!!If the manufacturers of this questionable item of equipment do not understand the basics of oxygen, air, depth and scuba diving in their most rudimentary forms they should NOT be making such equipment. Avoid all contact with this device. It is clearly not fit for purpose and certainly not fit for the minimum one star rating I am required to give.NM(Active diver/instructor for over 45 years)