A couple of quick observations:
There is NO way Strider is 240lbs in these pictures (unless he's like 36+ inches tall). If he's really 240lbs, then get some current pictures up ... or ... be truthful about his weight (or disclose that he's abnormally/unusually tall). Also, there's no pedigree posted ... who knows anything about the dogs behind this dog ... a huge pet peeve and red flag. This dog has very limited amounts of breed type. A nice pet quality dog should not be siring any litters, much less three! UGH!! Oh, I've also never heard of his breeder.
Gracie ... looks a cute pup ... referencing Rockport and Lionhearted pedigree, but not actually posting the pedigree is a continuation of the pet peeve and red flag. I've never heard of her breeder.
Halo ... seems to lack breed type (long muzzle, shallow chest, fine bone, etc.). I've never heard of her breeder.
Mia ... seems to have the most breed type of all their dogs ... never heard of her breeder ... and without a pedigree, who knows what "fantastic lines" are behind these dogs ... nor, how far back these "fantastic lines" actually are.
Available puppies ... there have been lots of tears shed over non-refundable deposits. Caveat emptor. Further, the pups look cute ... but so do all pups ... so, there's absolutely nothing remarkable about these pups (at least in terms of "bettering the breed," which is supposed to be the marching orders of every breeder).
Upcoming Litters ... if Strider is "by far the best dog I've ever seen" then whomever wrote this website needs to get out more. He's a nice pet, but shouldn't be bred (based on the pictures posted).
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While this breeder may be a nice person, it doesn't appear they have any idea what constitutes Mastiff breed type nor what it means to be an ethical breeder (i.e., only breeding for the betterment of the breed).