I always wanted to try Suuntos "Light Black" strap for the Core. It is Suunto's lightest and most cut-out strap made for the Core. It allows the most air flow under and around the Core and should be ideal for warm climates or summer time. This means you wont sweat as much under the typical elastomer strap and water also dries quicker. A additional benefit I found was that the "Light Black" strap has more stretch to it for a more comfortable feel on the wrist. I did notice that the buckles of both straps are the same size but the tang is wider on the "light black" strap. I can tell the weight of the LB strap is less. My Core feels so light and airy I cant believe the strap made that big of a difference.
How to replace Suunto Cores strap: I used two small flat-head screw drivers to unscrew the pins on either side of the strap. Place one flat-head on one side of the strap and hold it so it doesn't move. Place the other flat-head and unscrew the pin. Placing the watch down on a soft flat surface while doing this helps a lot. Dont be surprised if the factory over tightened the screws. You might have to use a very small flat head screw driver to pry the loosened pins out of the elastomer strap so you can get your fingers on it to pull them out of the strap and case of the watch.
When replacing the screws on the new strap, tighten the pins lightly snug.
Dont tighten the pin as much as the factory did or you will break the head of the pin off or strip the threads. Cores with lugs on the strap are the same procedure except you have to loosen two sets of pins per watch side.