This set contains five 50 pence coins carrying the reverse designs of commemorative 50 pence issued in earlier years and having military topics; all coins in the set are dated 2019.
The Royal Mint says:
"This year marks a significant milestone for the 50p - one of the nation’s most iconic coins. Over the last 50 years, the coin has been chosen to commemorate some of the most pivotal events in Britain’s military history. To commemorate this once-in-a-lifetime numismatic moment, The Royal Mint is delighted to present five military themed coins in one celebratory set.
Issued as silver Proof piedfort editions, the 50 years of the 50p military set contains five coins that are double the weight of their silver Proof equivalents. Coins featuring the 950th anniversary of the Battle of Hastings, the 50th anniversary of D-Day, the 75th anniversary of the Battle of Britain and two coins commemorating the 150th anniversary of the creation of the Victoria Cross medal are presented together for the very first time." | 
Search for this coin set on eBay 