Hi, i have been using them for 4 years .....
..... and now i have finally made a descent version of it.
4 neodymium magnets (22kg each on a flat surface!) + 1" ball head are holding easy 1 or 2 strobes on steel tanks.
You can use the holder also on aluminum tanks with a normal tank strap 50mm width. The holder fits 3l to 12l tanks.
The magnet surface have to be rinsed after each dive to prevent oxidation!
I only produce them on demand.
PM if interested .... greets, Hedwig.