The new and improved Butt Loks feature a hard plastic skeleton with soft, durable rubber on the sleeve. When properly sized to the rod, these securely lock the butt of the blank. Available in 3 standard sizes (Small, Medium, and Large) to fit full cork/duplon doubles and the thinnest 10-foot blanks up to the most powerful 13-foot blanks in shortened wrap or shrink-wrapped handles. The Duo model is for the angler switching from full cork/duplon to shortened or fully shrink-wrapped handles. Supplied with a rubber O-ring for precise alignment on buzz bars.