4” laser head is the laser head of the laser cutting machine that installed a 4” focus lens. The standard laser head is mainly used to cutting material less than 10mm. But if you want to cut thicker material, such as 17mm foam, the cutting edge would be bent after cut by the standard head. This is because of the focus lens characteristic. But don’t worry, our 4” laser head can help to solve the problem, 4” laser head will produce a more vertical laser beam, it will make the cutting edge be more straight and neat. Thus 4” laser head is more suitable for cutting thicker material.