Do you have Bumbo Infant Seat? They have just issued a Recall on the Bumbo Infant Seats and are offering Free Repair Kits, which includes a restraint belt. The seats are recalled because people were putting them on elevated surfaces and babies were falling out and some fractured their skulls. The instructions on the box clearly state to not put the seat on elevated surfaces, but the restraint belt is still a good addition to the seat.
NOTE: Their site is slammed when you get to the ordering page, you may need to try again later.