The website's name itself was a giveaway about its intentions. The "300mb" in the URL referred to the file size of the movies available on the site, which was remarkably small compared to the standard file sizes of movies. This made it easy for users to download movies even on slower internet connections.
: To evade legal action, the site often migrated to new extensions (e.g., .com, .ltd, .org, or .link) or used proxy mirrors. Emizentech Legitimate Alternatives
Using sites like 300mbmovies4u involves significant risks that were well-documented by the end of 2021: Illegality
Users could browse by genre, release year (specifically the "2021 Movies" section), and quality (480p, 720p, 1080p).