To make the primary small enough to fit into the narrow part of the cone, its bulky insensitive high explosive charges must be replaced with more compact "non-insensitive" high explosives that are more hazardous to handle. The higher yield of the W88, which is the last new warhead produced by the United States, thus comes at a price of higher warhead weight and higher workplace hazard. The W88 also contains tritium, which has a half-life of only 12.32 years and must be repeatedly replaced. If these stories are true, it would explain the reported higher yield of the W88, , compared with only for the earlier W87 warhead.