Guinness Surger for commercial use (ultrasonic vibration) (Not for sale) 10 new Guinness glasses, 350ml each 30 Guinness coasters The surger can be used with Guinness Stout for commercial use. It can also be used with Guinness Stout sold to the general public, but the foam may overflow due to the reaction with carbonation. Please be careful. A Guinness keychain is included as a bonus (^^) *We are not accepting price negotiations. Thank you for your understanding.