This item was used for one month when my baby was 4 months old, and my baby is now 5 months old. Pigeon Mother's Touch M x 3 I used these three in rotation, so I think there is little deterioration. Set of 3 silicone round nipples for baby bottles. - Quantity: Set of 4 - Material: Silicone - Shape: Round - Application: For baby bottles Thank you for looking.