Mattress, White, Material: Foam
Sealy Posture Perfect 2-Stage Hybrid Waterproof Baby Crib & Toddler Bed Mattress in Yellow | 5.75 H x 27.25 W x 51.63 D in | Wayfair
Amazon
Sealy Posture Perfect 2-Stage Waterproof Baby Crib Mattress and Toddler Bed Mattress - Hybrid Memory Foam & 150 Premium Coils - Made in USA, 52"x28"
Babylist
Sealy Posture Perfect 2- Stage Crib And Toddler Mattress in White Windsor Pearl Size 51.63" x 27.25" x 5.5"