The Kirk SQRC-3157 Quick-Release Clamp fits into the RC2 quick-release element of a Manfrotto head to convert it to an Arca-style quick-release system. This lets you "recycle" an existing three-way or ball head so you can remove and attach your camera more quickly. With just a quarter-turn of the sure-grip knob, the SQRC-3157 enables you to release the plate by sliding it; with a full turn, you can remove it upwards.
The SQRC-3157 is compatible with most Arca-style plates and mounts. Constructed of a rugged aluminum alloy and anodized to a scratch-resistant finish, the clamp features a bubble level as well as notched lines that indicate the position of your sensor's center, which enhances the precision of such tasks as panoramic photography.