The only problem I had was that when I got them from CP, about 1/3 of them were broken... UPS had managed to crush the top of the box. Cole Palmer made it good right away by giving me a credit, tho... and I still had more than I needed. The 250ml were perfect for blending up one 4 oz candle, and the 650 were for one 8 oz. I had tried several other things before, including styro and plastic cups, which melted in the microwave and didn't really seem like the "green" thing to do! joanne