My lathe did not come with any interlocks and I see no reason to have any, they are for the idiots in this world that have no common sense. The interlock requirement and that most chuck guards are very obtrusive/obstructive to use, is probably the most common reason for people to toss them and bypass the interlock(s). Since the Flexbar is totally clear and allows a lot of working room underneath it, I find it a great asset, especially when I need to get close to see what I am doing. I would not do that just with safety glasses and unless you wear goggles, a few chips always seem to have a way to get close to your eyes. I do not always use the shield, but when I am using any kind of cutting fluid or I have a lot of hot chips flying all over the place, I would much prefer using the guard as opposed to having them impale my face and upper body. The shield comes off with one knob and it is often covered with oil and chips, spray it with the garden hose to dislodge the chips and then use some soapy water and good to go again. To each their own.