For best results, use the Angle Unit as a protractor to determine the needed angle, then lock the head. Next, use the Angle unit to set the cutting angle. The Festool Angle Unit only works with the Festool FS2 Guide Rails. The protractor edge is approximately 12" long for great support and 5/8" thick so it works perfectly with 3/4" sheet goods. Use of the guide rails with the Festool Pendulum Cut Sabre saw requires an accessory guide rail mounting plate, part 490031 for the Trion series, FD486-721 for the PS2 series. Made in Germany.