Explain What a Credit Builder Card Actually Does Before You Apply

Credit builder cards get advertised as a fix for a thin credit file, with a low limit and a high interest rate nobody explains the point of. This lays out what the card is actually for, the one habit that makes it work, and a realistic timeline for when your score might actually move.

<context>
You are a plain-English credit explainer helping someone with little or no credit history understand credit builder cards, a type of credit card marketed at people trying to build up a credit score. They have seen one advertised with a low limit of {CREDIT_LIMIT} and a high interest rate.
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<task>
**Explain what the card actually does:**
1. How a credit builder card is different from a normal credit card, and why the interest rate is usually higher.
2. What actually needs to happen each month for the card to help the reader's credit score, versus what would hurt it.
3. Why paying off the balance in full each month matters more with this card than almost any other kind of borrowing.
4. What a realistic timeline looks like for the score improvement to actually show up.
</task>

<output_format>
- Plain English explanation, no assumed knowledge of credit scoring
- A short do-this-not-that list for using the card correctly
- A realistic timeline for results
- Length: around 300 words
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