The BDX Cocktail Cube is made of High Density Polyethylene and is food and dishwasher safe.
From Dave Arnold:
"The Science: For years I scoffed at the numerous bartenders I heard wax poetic on the virtues of shaking cocktails with one big ice cube. One year in front of a large audience I ran a test intended to prove that big ice cubes were all show. I shook with different types of ice and dumped the drinks into graduated cylinders to measure the amount of foam the shaking had produced. To my surprise, and embarrassment, the large cube had a positive, repeatable effect on foam quantity. I don’t know why the big cube does a better job, it just does.
I instantly changed my tune, and insisted that all shaken drinks at Booker and Dax would henceforth be made with large cubes. But remember, that one big cube does not dilute as much as the smaller cubes do –which isn’t good. The solution is to add a couple smaller ice cubes to your tin along with the big cube before shaking. The extra cubes don’t seem to mess with the awesome texturizing effects of the big cube and give all the extra dilution you need.
The Problem: Big ice cubes cost a dollar or more. And when you use one for every shaken cocktail that can add up.
The Solution: Creating a product that mimics the size, shape, and shaking characteristics of a large 2-inch ice cube. That is the heart of the BDX Cocktail Cube. When shaking a cocktail with the BDX Cocktail Cube the problem of DILUTION -which can be provided by any type of ice, small, medium, broken, that the bartender has available—is separated from the problem of TEXTURIZATION –which is provided by the reusable BDX Cocktail Cube. It can also fit into all three shaker sizes: Boston, Cobbler, and French."