Replacing the rubber seal - Aluminium Windows

Trying to fix our very old aluminium windows. The rubber is cracked and has tightened. I am not sure where to go to find a replacement (I did try Bunnings, but no luck).

Can I use something different instead? Or do I need to find the exact type of rubber? (We are replacing the rubber in all the windows.)

Hi
How old are these windows & what brand are they? Should be on the pull handle.
The simple solution is to remove this glazing rubber on 2 edges of each glass pane at a time and caulk these with black silicone. I say 2 sides to allow the new silicone to cure for 48 hours before you do the other 2 edges. A tidy job and it will be waterproof too.
kaibis