Sample-to-full-size conversion
Many buyers received a free sample (often bundled with sheet masks) and purchased the full size after liking how it felt, indicating effective trial marketing.
Ingredient reputation (madecassoside)
Reviewers cite trust in Mediheal's madecassoside line, associating the ingredient with soothing/calming properties from prior mask use, which pulled them toward the sun serum.
Influencer/YouTuber recommendation
Several reviewers explicitly mention buying because a Korean or international beauty YouTuber recommended it as a good daily sunscreen for under makeup.
Repurchase/loyalty
A large share of reviews are explicit repurchases or stockpiling during sales, citing consistent performance as the reason for returning to the product.
Promotional bundles and price
Buy-one-get-one-free (1+1) sales and 'trio sets' at Olive Young are repeatedly cited as a trigger for purchase, alongside general comments on good value/cost-performance.