Powerful brand name that was based on the word "muscle".
The name "muscler" has seven characters and only two syllables. Two syllable names make popular global brands. Two syllable names are used by established brands like Gillette, Walmart and Honda.
Muscler.com is a .com domain. Dot com domains are the most desirable top-level-domain in the world, famously used by websites like facebook.com. Owning a .com says that you own the word "muscler" online.