Pigeon Mother's Milk Real Feeling Nipple for baby bottle: SS size x 3, S size x 2 Regarding usage period and frequency: ▪️SS size: Used from the end of April 2025 for 1 month ※Since I was rotating 3 pieces, the usage frequency of one piece is extremely low. ▪️S size: Used from the end of May 2025 for 2 months ※I was rotating 2 pieces. Both are used items, so please purchase if you don't mind minor scratches or yellowing. Since the usage frequency per piece is low, I don't think there is much yellowing. ※For reference, I will post comparison photos with a yellowed one of a different size. (Used from October - 3 months) Due to shipping, the nipples will be sent in a flattened state. Thank you very much! ☺︎