Hollow has double walls -- the inside wall is lower than the outer one and the gap between the two is so narrow, a special nozzle has to be used to drop anything inside it.
The nozzle, which can be attached to any optic used to pour nips of spirit measures, sits on top of the drinking glass, filtering liquid into the walls of the vessel.
Once the optic is removed, it is extremely difficult to pour anything into the sides because the center is hollow and bottomless.
"If you were to drop anything into the glass, it would go straight through the middle. If any drug did land inside the walls of the glass, it would be such a low percentage that it wouldn't have an effect," Martin said.
I love ideas that are the simple "why didn't I think of that" type. I'm not fooled into thinking that this is tamper proof. Anyone with a small sprayer similar to the pressurized breath fresheners and a decent aim with enough time could circumvent it, or, buy the glass as well and carry the attachment.
However, level of difficulty has been raised for those who do that sort of thing, which is good.
The downside, you've been relagated to walking around with an adult version of a "sippy cup".