A clamping mechanism particularly for clamping a vibrator to a reinforcing bar. The clamping mechanism provides a slot which intersects a channel. The channel is longitudinally open in one direction at one side of said intersecting slot and longitudinally open in the opposite direction at the other side of said intersecting slot. A reinforcing bar or other member to be engaged first enters the slot then moves into the channel. Once in the channel, the bar or other member is positively retained therein.