Works as intended on my Modulus Demolisher. The part you twist with your fingers is right next to the battery plate as if someone stuck a thin button battery on the side. Not having too much trouble with it myself, but it might make it difficult for someone else to get it off as it's flush with the side and larger fingers may have some issues. As I don't really intend on repainting my blaster, the two pack, (if I had seen it I would have got it instead) which is lower cost for 2, might have been better as they have an easier to grab head on them.
Quick delivery by USPS. Didn't have to wait too many days. Then again, I'm in Washington anyways.