Guys, just in case some of you don't really understand why tubes are recommended for some Panerai, I thought I should explain (I'm always having people asking should they have tubes fitted when they order a strap from me, and often they don't understand what tubes do).....
Tubes are really designed for use with Luminor cases, and specifically those with the traditional screw bar system (rather than the newer push release bar system as on the 233 etc.). On these watches the screw bar screws directly into the watch case (it passes through one lug and screws into the other). When wearing a leather or rubber strap on the watch the friction between the leather / rubber strap and the screw bar can start to loosen it, and in the worst case this could be responsible for the bar coming out and the watch falling off your wrist. By using tubes in the strap the friction acting on the screw bar is greatly reduced (much less friction if the only thing touching the screw bar is the inside of a steel tube) and so is the risk of the screw bar becoming loose.
If your watch is one of the Luminor cases with the newer style push button release mechanism then you don't need tubes in your strap (the bar can turn all it wants - it won't release until the button is depressed), but they won't do any harm i.e. the bar will fit through the tubes fine. For Radomir cases tubes are not required as the strap attached in a completely different way.
I'm sorry if this is obvious to you, but from the comments above I guessed understanding what tubes are designed to do might be useful
Rich