The catalyst plated in the discharge tube coordinates unique electrode treatment technique to make discharge more stably. Optimal operating current: 22 mA. Optimum working water temperature:15-35 degrees. The laser tube after generally work 3-4 hours should to pause for about 30 minutes. This laser tube should be used and placed under the normal room temperature in the cold weather.(In case of cooling water frozen as the weather getting colder). We have warehouses in the USA, UK, DE and AU. For those customers who live in the US, UK, DE, EU and AU, we will send item from the corresponding warehouse. For those customers who live in other countries, we will send item from our foreign warehouses if available, otherwise from China. E-mails are answered Monday through Saturday. Please allow up to 48 hours for a response to your message 3. The item "40W CO2 Laser Tube Water Cool Sealed for Engraving Engraver Cutter Machine" is in sale since Monday, January 8, 2018. This item is in the category "Business & Industrial\Healthcare, Lab & Dental\Other Healthcare, Lab & Dental". The seller is "ukdirectseller" and is located in Dayton, New Jersey. This item can be shipped to United States.