Speedo 7cm Brief Sn54. Speedo Swimming Mens Briefs ECO Endurance+ 7cm Brief. Our classic brief, now with better eco-credentials. We’ve given our much-loved 7cm Brief an update using our Endurance+ fabric. Retaining the comfy, modernised fit and drawstring waist loved by swimmers the world over. Quick to dry and 100% chlorine resistant, it’s ideal for regular training sessions.