Used to clamp on to 1-1/2" aluminum speed-rail .
Speed-Rail® Starter for 1-1/2" - 3-1/2" to Junior Male
Speed-Rail® Starter for 1-1/2"
Speed-Rail® Starter for 1-1/4"
Speed-Rail® Starter for 1-1/4" - 3-1/2" with Junior Male
Plate Slider Bracket Mini for 1-1/2"