The composite ones are legit, I love those. Make sure you're shimming from both sides so you get two triangles that form a rectangle(ish) shim with parallel top and bottom for maximum effect (you probably already know this).
@Dawgz Lookin most excellent my man, u did a great job ??. Ive never even went as far to go both ways like that lol. Honestly might be the best example of how to properly level an acrylic tank on the forum.