At 8 inches tall, the Birch Kids Natural Mattress is a bit smaller than the Birch and Birch Luxe Natural Mattress, meaning the Waterproof Mattress Protector and Organic Mattress Pad will fit more loosely on this mattress. Customers are welcome to purchase either the Waterproof Mattress Protector or the Organic Mattress Pad with their Birch Kids Natural Mattress, but for optimal protection, we recommend adding the Accidental Damage Coverage to your order.