You can pick them up at any academy. Looks like a cheap seat cushion with straps. They are uber inexpensive, and I would just have one period.http://www.basspro.com/Type-IV-Flotation-Cushion/product/44754/?cmCat=
All Personal Flotation Devices (PFDs) must be U.S. Coast Guard approved, in serviceable condition, readily accessible, and of the appropriate size for intended user. See Life Jackets for more details on PFD types.All children under 13 years of age in or on vessels under 26 feet in length
must wear a U.S. Coast Guard approved wearable PFD while underway. Underway means not at anchor, made fast to the shore, or aground.
All vessels, including canoes and kayaks, must be equipped with one Type I, II, III or V wearable PFD for each person on board. A Type V PFD is acceptable only if used in accordance with the specific instructions on the label of the device.Vessels 16 feet and longer, excluding canoes and kayaks, are required to be equipped with one Type IV throwable PFD
in addition to the Type I, II, III, or V PFD required for each person on board.
Inflatable PFDs are authorized only when used in accordance with requirements as presented on U.S. Coast Guard approval labels. Inflatable PFDs are not approved for use on personal watercraft, waterskiing, or other high speed activity.