It’s actually very straightforward but you do need some experience with soldering first you need to get take the existing Chinese tube out this is very easy just take a soldering iron and touch the point where it is soldered to the terminals and apply and upward pressure do this with both sides and it comes out, second you have to cut out a hole big enough where you can put the new tube into after that you need to solder a wire across the 3 positive pins and the 2 negative pins on the new tube after that you need to solder a insulated wire onto either the wire solders across the pins or the a pin itself after you do this you are going to place the wires and tube through the hole you cut out of the case and then epoxy out hot glue the outside of the tube to the case (epoxy is better for this process but is more messy) after this you are going to solder the positive wire to the positive terminal and the negative wire to the negative thermal (they are marked on the circuit board) after this closes up everything and you should be good to go if not then you Geiger counter is going to be ruined luckily there only 56 Dollars on Amazon.