Suits most older spa lights, and any with a wedge fitting. GE912 (12W) GE939 (5W). Note many people have used lights over 12W, which can melt the light fitting, and have used under sized 5W globes that appear too dim. These are the 12W version.
You can also upgrade to a MultiColour LED Globe like these.
O'Ryan P1110 12W 12V GE912 Mini Wedge Light bulb