All-in-two (AI2) diapers can be confusing, as there are essentially two types of all-in-two diapers, and they are quite different. However, they are all named for the fact that there are two parts: the waterproof outer and the absorbent layer, and these two parts are separate.
Hybrid all-in-two diapers are diapers that can be used in multiple ways. The most common is as a cover with either disposable insert or a reusable insert. The waterproof outer shell is usually made of PUL (polyurethane laminate). If the shell remains clean, you can replace just the insert when soiled and re-use the cover. Some brands offer the choice of using a disposable insert, which you throw away when soiled, or a reusable insert, which you put in a wetbag to be washed when soiled, while others just offer the choice of reusable inserts. Some brands have the insert snap into the cover, while others have the insert lay in the cover. Hybrid diapers are generally fairly customizable, as you can select how many and which type of insert to use.
Snap-in or lay-in all-in-two diapers are simply all-in-one diapers that come in two parts. Rather than having the absorbent layers sewn into the waterproof outer layer, the absorbent layers are separate and can be snapped in or lain into the waterproof cover (these are often called "soakers". This allows for a faster drying time, and often for a more customizable absorbency, since you can use none, all, or part of the absorbent soaker layers. These types of AI2 diapers usually don't have a stay-dry feeling. Many AI2 diapers are WAHM/Etsy/Hyena Cart made and have a hidden layer of PUL underneath a colorful outer fabric, while others have the PUL on the outside. Confusingly, some diapers that are technically snap-in AI2s are marketed as AIOs. These diapers are generally not as customizable since they come with a pre-set soaker.
What do they look like?
Hybrid: Best Bottoms cover with hemp insert
Hybrid: Flip cover with reusable stay-dry insert
Hybrid: Flip disposable insert (pictured alone)
Hybrid: Flip cover (pictured without insert)
Snap-in: Doodle Dype
Snap-in: Doodle Dype
Snap-in: Fishnoodle (showing soaker unsnapped from shell)
These can be sized or one-size and may close with snaps or velcro.
What are the pros and cons?
Hybrid: Flexible, cover can be reused so don't need to invest as much.
Snap/Lay-in: Often have cute prints on outside of diaper.
Hybrid: If using the disposable option, still contributing waste to landfills, and disposable inserts can be pricey.
Snap/Lay-in: Entire diaper needs to be washed each time. Can't customize absorbency.
How do I care for my AI2 diapers?
Prepping your AI2 diaper depends on whether the inside of the diaper is made from synthetic or natural fibers. If it's made from synthetic fibers, simply wash once. If it's made from natural fibers like hemp or cotton, wash 5-6 times prior to use. Most hybrid AI2 shells (covers) are synthetic and can just be washed once. Most snap- or lay-in AI2 diapers are made of natural fibers and need to be washed multiple times. After prepping, wash using your normal cloth diaper wash routine. Be sure to attach the laundry tabs for velcro diapers. Hybrid AI2s used with disposable soakers must have the soaker removed prior to washing. Hybrids and snap- or lay-in AI2s can be washed as one piece; there is no need to separate the soaker if you don't want to do so. After the diaper is washed and dried, if the soaker was removed you'll need to replace the it before use. Some people do this for all their diapers immediately and have a set of "pre-loaded" diapers ready to go; others replace as needed and add the soaker as they use the diaper.
What are common brands of AI2 diapers?
Best Bottoms (no disposable option)
SoftBums (no disposable option)