Hi Igor and welcome. One of the most comfortable Braces is the SBA4: budsgunshop.com/product_info.php/products_id/110012/sb+tactical+sba4+a4+ar+platforms+black+6-position+adjustable ------- Cheers, stay safe and enjoy!

Good evening to you!! You can replace the original buffer tube with one that has slots. Once replaced you can use the SBA tactical brace. Hope this helps. Have a good rest of your day.

Hi Igor, If you want to add an adjustable brace, you would need to replace the buffer tube with a slotted one. budsgunshop.com/product_info.php/products_id/146750/tacfire+mil-spec+buffer+tube+black+hardcoat+anodized+aluminum+for+ar-15 ,
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Then you could add this brace budsgunshop.com/product_info.php/products_id/143778/sb+tactical+sba3x-01-sb+sba3+brace+synthetic+black+5-position+adjustable+for+ar-platform+tube+not+included ,
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Stay safe & have a great day!