One of the best braces available - SB Tactical SBA3 5 Position Adjustable Rifle Brace

It's a great brace, I have a few, never had any issues for years. It's the lightest SB Tactical AR brace. Lighter braces exist but are hard molded and thin, and therefore less comfortable. It's not perfect, the bottom WILL bend and flex with a lot of pressure into it, but you can do a few things to mitigate this, such as staging a sling by wrapping it through the flaps. Length of pull on a carbine tube is good for me at 6 feet, but is maybe one position shorter than perfect. These work fine on an A5 length tube if you really need more LOP, but will not collapse fully flush.