Dear All, We are so glad to present the best eXpromizer clone to you: Even better quality than the original ones, 1, spring : use copper material (thicker copper spring, better bounce) 2, smooth polish 3, change air flow without removing the bottom, just unscrew a bit 4, very easy to fill 5, prevent oil leak design EXW price US$ 17/PCS. Best regards, Jenny liu Skype:jenny_4144 Mobile & Whatsapp: 86 13048876779 Web Address: www.hekvapor.com E-mail Address: jenny@hekvapor.com