Erlenmeyer flask size?

[stz]

I've got some of those from cream supplies. They are alright and the price was right too. However they do not really get much exposure to heat, never boiled in them. I've broke a 'proper job' one before just by rinsing it with warm water and dropping in the stir bar, though in defence of the expensive ones it was at least 10 years old.

 

[Bigcol49]

So it is not really Boro 3.3

Hi!
I've had no problems with mine, so I have no doubt that it is, as advertised, Boro 3.3.
As @foxbat has written, the instructions are probably an abundance of caution - covering their back.

 

[BeerCat]

I banged mine against a pyrex jug and cracked the jug but the flask was fine.