Loyalty to the original Birch Juice sunscreen
Many buyers already used and loved ROUND LAB's non-tinted sunscreen and purchased the tone-up version to try a tinted alternative from the same trusted formula.
Desire for a no-makeup 'skip foundation' product
Reviewers frequently bought it specifically to replace foundation/BB cream on low-effort days, citing the tone-up plus SPF combo as a one-step solution.
Bundle/set value with cleanser gift
The special set price and included cleanser sample were cited as a purchase driver, with several buyers saying the promotion made it an easy add-to-cart decision.
Repurchase/repeat customer behavior
A notable share of reviews explicitly state this is a 2nd–5th repurchase, indicating strong retention once tried.
Sensitive/dry skin reputation
Buyers with sensitive or dry skin sought it out based on the brand's reputation for gentle, hydrating, low-irritation sunscreens.