The original version of the Z-Vibe had a single-ended design. It came with one Probe Tip. You would turn the Z-Vibe on by twisting that Probe Tip into the handle. And you would replace the battery from that end as well by untwisting the tip.
We later came out with a newer version: the end with the Probe Tip (the end that goes in the mouth) is now sealed off from the battery. And you turn it on/off by twisting the "Switch Tip" at the opposite end of the handle. For a while we called this new version the "DnZ-Vibe" to distinguish it from the original version. But we eventually discontinued the original version since the newer version is much improved, and since then we've gone back to just "Z-Vibe."
All of these options are vibrating oral motor tools that provide varied sensory input for oral massage, stimulation, awareness, exploration, and more.
Please note: if you suspect that any water, moisture, or saliva has gotten into your device, simply disassemble the unit and allow the parts to completely dry on a towel. And to turn the unit on, twist the Switch Tip into the handle *just* until it starts to vibrate. Any further will not increase the vibration, but significant over-tightening (although hard to do), may damage the motor.
For assembly instructions, click here.