This is Harken's 22 mm high beam track with an internal channel for mounting using pre-existing holes which have unusual spacing, or need variable spacing due to obstructions, etc. The track is secured with bolt slides (included) which slide in the channel, and have a hole for the fastener (not included).22 mm Small Boat Captive Bearing (CB) Track is used on travelers, adjustable genoa leads and as mainsail mast track. It comes in low-beam or high-beam configurations. Use low-beam track when it can be supported at each fastener hole; high-beam track is appropriate when spanning a cockpit or other unsupported area. Refer to the 22 mm High Beam Track Spanning Chart on our website for details.High-beam track is also available with pre-drilled (fixed) holes at 100mm (3-15/16") intervals; however Retrofit Track with 4" hole spacing is available for replacing pre-existing travelers with 4" fastener spacing (eg Nicro Fico, etc.). Maximum mainsail area for 22 mm track ranges from 7.5 m (80 ft) for multi-hulls with mid-boom sheeting and standard cars, to 18.6 m (200 ft) for mono-hulls with end boom sheeting and high load cars Hard anodized aluminum construction Fasteners: 5 mm Hex Head Can be bent to your specifications, please call for details Min. bend radius for 2-7/8" cars: 1.07 m (42"); for 4-1/8" cars: 2.03 m (80") Note: due to its length, track over 8 ft long must be shipped via truck or air freight