Ron Guth: In 1853, a new Mint Act lowered the weight of Half Dimes in response to a rise in the price of silver. This meant that all of the old silver coins still in circulation were worth more than their face value, thus they needed to be recalled and reminted at the new, lower weight. To denote the weight change, the Mint added arrows on either side of the date, making it easy for anyone to quickly identify the new coins versus the old. The Mint repurposed an untold number of old silver coins into a whopping 13 million 1853 With Arrows Half Dimes -- easily the largest mintage of any Half Dime from the beginning of the series in 1794 to the end in 1873.
Though this is a very common date, there are lots of type collectors who need and want this date for their collections. Hundreds and hundreds of Mint State examples exist, mostly in MS63 and MS64. Even Gem are common and only in MS67 does this date become truly rare. The finest example is a single PCGS MS67+.