An additional active button may allow purchase while the main button requires size selection.
Sticky mobile purchase controls retain variant and price
A sticky purchase control must share product-selection state without covering information or focus.
Research context: Baymard · Product-list information ↗
Start with a clear standard control. Add a sticky control only when long product pages justify it.
Try the pattern
Task and expected result
- 01
On mobile, locate purchase choices and check the size requirement.
- 02
For a sticky control in your store, test unavailable and missing sizes.
- 03
Zoom the page: no fixed control may cover focus or policies.
How to investigate value
Ask shoppers to explain their variant choice and fit. Later measure confirmed purchases per eligible product visitor, with return reasons as follow-up.
Watch for side effects
Wrong sizes, unknown details shown as facts, mismatched expectations and product-related support/returns.
This is a proposed investigation, not a measured result. Choose one hypothesis and define the audience before testing.
Build a measurement plan for this concept ↗