The PRO-LOKS NEX-GEN Upgrade is for customers who have purchased PRO-LOKS in the past and would like to upgrade from their Classic PRO-LOKS to the NEX-GEN. You need to have available your "Y" stainless steel posts to add upgrade to. Please refer to Video page on PRO-LOKS.com. You MUST purchase the PRO-SLEEVE if you don't currently have them installed.