Never heard of them before. WHOIS lookup states the site (if it is horrorfxstudio dot com) was registered in August of this year, with only a 1 year registration. That's not good. It appears that they also "curate" their reviews, meaning they can remove/change any of them.
For a company supposedly in the USA, it is using a Swiss secondary registration that hides the identity of the site owner. Lots of the info is in European format, and their social media is filled with duplicate info, but all of it is very basic/generic horror trivia/info, using likely stock illustrations, and nothing of their actual product.
One of the supposdely real maker pics I did a google image search is actually from this guy:
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Many reviews are dated before the site even existed. All of the masks I imaged searched are posted on MANY other suspect sites, but it looks like this site did some basic photoshop to add the smoke effect on black background so it was harder to locate the copies. The Freddy mask for instance - the actual still photos of the mask don't match the video showing the guy putting it on (they are different molds).
Also the prices are really too good to be true. Real quality latex masks cost hundreds.
My opinion: wouldn't trust.