For those who are curious, Safe chemistry means no risk of venting with flame or explosion. IMR will just sizzle out in case of any failure.
Please note that due to their inherant safety, Most IMR cells don't have a protection circuit built in. They should never be discharged below 2.5 volts or cycle life/performance will be reduced. Maximum charge voltage is 4.25 volts. Please check your cells with a volt meter during initial charging to be sure that your charger cuts off below this level, or cycle life will be reduced.