Never heard of, so also never ordered from.
My experience of similar offers is that a site gets hold of some end-of-season or previous year's stock.
Then they slap a huge discount on the least desirable sizes, the XXL and the XXS.
These will be the 70% off.
Then they set perfectly normal discounts on the big selling sizes.
People who haven't done their homework gets drawn to the sites by the possibility of big discounts, and end up settling for a smaller discount on a size they can use.