All three boxes come as vouchers, redeemed at a pickup point. Vouchers post as documents, so postage is HK$10 however many you buy.
Durian snowy must travel frozen and custard can't be frozen at all, so the two can't share a parcel. Redeeming means both arrive in the condition they're meant to.
Buying more?
Orders over HK$1,000 get 10% off the whole order. Four boxes of durian snowy is HK$1,232 → HK$1,108.80.
