This is info from the USPS website. These absolutely have to go by Parcel Select (Ground). Never send by anything other than ground service. BTW, ground service is expensive and slow.
USPS Packaging Instruction 3C
Flammable Liquid or Gas Lighters
A lighter equipped with an ignition element and containing fuel is classified as a Class 3 flammable liquid. A lighter containing a flammable gas is classed as a Division 2.1 flammable gas. A lighter that contains either flammable liquid or flammable gas is permitted in domestic mail via surface transportation only with prior written approval, provided all the applicable requirements of 343.25 are met.
Proper Shipping Name and ID Number
Lighters or Lighter Refills, UN1057.
Required Authorization
The design of the lighter must be certified by the lighter testing agency authorized by the DOT Associate Administrator for Hazardous Material Safety, per 49 CFR 173.21(i) and 173.308, and an Approval Number (LAA****) must have been issued.
Mailability
International Mail: Prohibited.
Domestic Mail: Permitted only via surface transportation.
Required Packaging
Primary Receptacle
The design of the lighter must be approved by DOT (see “Required Authorization” above).
Cushioning Material
Sufficient cushioning material must be used to absorb shock and protect the lighter from breakage.
Outer Packaging
The packaging must be designed to protect the lighter‘s sparking mechanism from accidental ignition caused by friction or external pressure during transport.
The outer packaging must be of sufficient strength to prevent the inner contents from breaking or bursting through.
Marking
The address side of each mailpiece must be clearly marked with “Surface Only” or “Surface Mail Only” and “Lighters” or “Lighter Refills” followed by the LAA**** Number.
A complete return address and delivery address must be used.
Note: A legible photocopy of the PCSC manager‘s approval letter must accompany the mailing at the time of deposit.
