Savvy Rest also offers innerspring mattresses, including the SerenitySpring (View Price on Savvy Rest) and the Earthspring mattress (View on Savvy Rest). Both are also Greenguard GOLD certified. The SerenitySpring is customizable, both for the top layer of latex and the underlying coil unit. This makes it one of the best choices for a hybrid latex mattress. See our full review here. The Earthspring is a lower-cost 9-inch innerspring mattress made without chemical flame retardants and ideal for children or small adults. It is only available up to Queen size and has a Bonnell design innerspring unit (where the coils are interlinked). This kind of coil unit creates more motion transfer, meaning its best for solo sleepers. The Earthspring mattress also isn't customizable and is fully assembled before delivery.