Washington (CNN) — Small pocketknives and an array of sporting equipment — banned from aircraft cabins in the wake of the September 11, 2001, terrorist attacks — will once again be allowed in U.S. planes, the head of the Transportation Security Administration said Tuesday.

Knives with blades that are 2.36 inches (6 centimeters) or shorter and less than a 1/2 inch wide will be permitted on U.S. airline flights as long as the blade is not fixed or locks into place. Razor blades and box cutters are still not permitted.

Two golf clubs, toy bats or other sports sticks — such as ski poles, hockey sticks, lacrosse sticks or pool cues — will also be allowed in carry-on luggage.

Transportation Security Administration head John Pistole said the changes will take effect April 25 and will bring the United States into alignment with international rules.

Some security experts say security improvements since the attacks — most notably reinforced cockpit doors, better intelligence and motivated passengers — have made the strict prohibition of small pen-knives unnecessary.

Small knives permitted in carry-on luggage must meet all of the following requirements:

Permitted:

• The blade must be no more than 2.36 inches or 6 cm in length – from tip to where it meets the handle or hilt
• The blade must be no more than .5 inches in width

Not allowed:

• Knives with locking or fixed blades 
• Knives with molded grips
• Razors and box cutters

If a passenger is unsure if an item meets the above requirements, TSA recommends that the item be placed in checked luggage.

The final decision rests with TSA on whether to allow any items through security checkpoints.

Click here to read about other changes to the Prohibited Items List.

For the complete CNN story, go here.