Nolol maalmeedka, waxaan badanaa u tixraacnaa tuubooyinka biraha si wada jir ah sida tuubbooyin bir ah, laakiin berrinka jarista tuubada, waa inaan kala saarno in birtu tahay tuubbada birta kaarboon, biibiile bir ah oo silikoon ah, tuubbo bir bir ah, birta birta ah ee titanium ama aluminium daawaha ah . Sababtoo ah qalabka kala duwan ayaa kala duwan ...
Akhri wax dheeraad ah