This is a jig/fixture, actually four of them, that will hold the frog points in place at the proper angle for soldering. The fixtures are for the following frogs: #4.5, #6, #8 and #10. Others could be made but so far these are the frog angles I've needed. They are designed to hold Code 55 rail but sometime when mine print one channel is a little narrow and I have to widen it which doesn't take long. I guess someone could widen them more for Code 83 or possibly Code 100. You can find the files to print this on my thingiverse.com account ( HERE ) and on my website here.... http://1fatgmc.com/RailRoad/Trackwork/page-33.html You can find all the files to 3D print this object and others on my thingiverse.com account ( HERE ). Sumner