Fits well in my HP21. Easy to use.

The product fits correctly, accommodates the rechargeable AA cells properly, and the calculator works well again. The workmanship of the product is excellent.

These holders are a perfect fit. However it is worth noting that you should use **flat-top** AA cells, not the usual type with a button on the positive end. The original HP packs used flat-top cells. They are slightly shorter so the springs compress more, allowing the pack to be removed easily. Using button-top cells both the original packs and the Calculator Store packs are very hard to remove.