A friend on Capitol Hill e-mails:

This provision was included to correct a mistake that was made several years ago in the JOBS Act, when the excise tax on archery arrows was changed from a percentage tax to flat rate of 39 cents. As a result of the imposition of this flat tax rate, producers of wooden practice arrows that cost 30 cents each are now required to pay 39 cents tax on each arrow – more than doubling the cost of these arrows.This provision is not unique to the bill now pending before the House of Representatives: it has been included in every version of the tax relief extenders bill considered by the Senate, including the version that recently passed the Senate 93-2.