Perhaps depends on which spring. My Mongoose has a very small spring and then a larger spring which is the Material Clip spring. I haven't tied on it yet, but my Patriot has the same SMALL spring and I don't think it is a material clip but a part of the vise itself. I think the material clip will be quite useful to me as I saw a man tying flies in my fly tying class using it regularly and it looks very useful to me.