Engineered For a Wedge-tight fit. Wedge-shaped components slide in for a snug, stable fit Type B seat mounts are designed to "lock" into the post; Engineered to prevent unintentional detachment; Heavy-duty bushing with peripheral bearing system and exclusive "crush ribs" are individually sized for exact fit; Tubing is precisely-sized and satin-anodized finished; Tubing comes in several styles. Pedestals come in several lengths, including patented "J-Slot" adjustable height; Precisely positioned locking tab positively locks post to base; Wedge' bushing locks in with a tight, solid fit; 2-Point stainless steel riveting strengthens the bushing; Strong base design has reinforcing ribs and improved profile to withstand the toughest conditions; Bead blasting closes aluminum porosity. Brushing process provides long-lasting high-sheen finish; Specifications: Diameter: 3/4"; Length: 13";