Celcius Reformation “CTW MX-4“ Gearbox

How to install Celcius Reformation Gearbox into the lower receiver. 2:17 Standard Selector and High Speed Selector Installation 2:55 Selector Switch Board Plate (Why it is necessary) 3:15 Right Selector Lock Plate Installation Guide 4:00 Inserting the gearbox into the lower receiver 5:00 Testing the alignment of bevel gear and pinion gear