All-metal structure (panel 6mm aluminum alloy): The bottom shell is made of 2mm high-strength cold steel, and the bottom is made of high-quality non-slip mats. 4inches(100mm-110mm), Inside Diameter: 16mm-20mm, T. OR, you may choose to have a replacement. We will reply you ASAP. Our aim is to provide Top Level Customer Service, normally so we will try our best to solve any problem you have.Our customer-oriented service strives for. Business time: GMT8 (9:00-18:00) from Monday to Friday. This item is in the category "Business & Industrial\CNC, Metalworking & Manufacturing\Metalworking Equipment\Metalworking Lathes". The seller is "malolomall" and is located in this country: CN. This item can be shipped worldwide.