The key is compatible with KW1 and KW10 keyways, which are very common in standard residential door locks (e.g., Kwikset).
Here is a long-form description based on the product’s purpose: 191 - KW1 Rainbow Key Blank Overview {RainbowKey}
A decorative "Rainbow Key Chain" is available, featuring the text "THE JOY IS IN THE JOURNEY". The key is compatible with KW1 and KW10
Tutorials exist for creating a macrame rainbow keychain using cotton cord and yarn. {RainbowKey}
Clear acrylic rainbow key shapes are popular for personalized crafting, jewelry, or badgereels.
Rainbow tables (Oechslin's paper) are used in cryptography to increase the success rate of attacks using hash functions.