Actually their English languge website is useless, you can't contact them through the site, though their products are available online. Their Korean language website looks like its very happening but obviously we cant figure that out.
They are well tested by a company that focuses on perfecting a handful of exclusive products. So the product seems good. But as for accessibility and any refund process, I'm not sure how good they are.
Teralium seems to be a rather unheard store, with not many clients in this part of the world. There is no mention of clinical studies or scientific research of their products.