Question: What size stopper does it take?
Answer: It's a 24/40 glass joint. The 24 indicates the inside diameter is 24mm.

Question: What is the angle of the joint
Answer: The two joints are at a angle of 75DGR.

Question: Is this a graduated Erlenmeyer?
Answer: No, this series of erlenmeyer only mark capacity.

Question: what is the largest size of RBF that this accepts?
Answer: I have been able to fill 500 mL RBFs (24/40) on each of the three receivers.

Question: Is the bottom section made of rubber?
Answer: This funnel is made of borosilicate glass 3.3 except the glass disc.