The Richell S-3 straw set is made of silicone rubber. Compatible with B 1521B. This is one set out of a pack of two. The box is torn. I was keeping this as a spare. Please refrain from purchasing if you are sensitive to imperfections. The box will be folded for shipping. - Brand: Richell - Model: S-3 - Straw Set: 2 sets - Material: Silicone rubber - Temperature range: 140°C to -20°C Thank you for looking.