But how quick do they explode once the sand destroys the anodization?
I think all the performance of this block is in the enamel paint, if that gets worn thru you are supposed to throw it out. I think the anodization is there just to make the paint stick. The failure of a wheel pulley means you have to flag out your flag, swim in and replace the pulley. If this aluminum block fails --- that is if it gets to the bare aluminum thanks to the sand, then it should wear straight thru the bridle line and instead of replacing a pulley you get to replace a pulley and a bridle. Or maybe these wear so slow you can replace them at the same time you replace your bridles for wear?
We'll see, the test is what these look like after 2 years of use, better or worse than pulleys.
The friction numbers for one of these new is really good for a sliding block, it would be great if they didn't wear too fast. I like the ronstan orbit block kite pulleys a lot if they fail you can kite back in and replace the pulley because it has a line thru the hole to catch your bridle.
But even if these sliders are supposed to be disposable it could be a lot cheaper than a ronstan orbit block.