WASHINGTON, D.C. - Customs and Border Protection issued a solicitation for contractors to begin bidding for the border wall contract.

In the request, CBP lists its requirements for several 30-foot long prototypes to be built for inspection.

The CBP solicitation has many requirements for contractors, including a height of at least 18 feet and that the wall be made to deter any punching through the wall with hand-held items like a sledgehammer or welding torch for 30 minutes.

The wall requirements also state that the wall should prevent digging or tunneling below it.

You can view the solicitation overview here.