1825 Extension Kit: K2 - Advanced Trains is an expansion for 1825, an 18xx game. It contains: 5 trains of type 3T (phase 3). 3 trains of type U3 (phase 3). 2 trains of type 4T (phase 4). 3 trains of type 2+2 (phase 4). 2 trains of type 4+4E (phase 4). Ownership of 1825 Unit 1 or 1825 Unit 2 is required. The advanced trains are not recommended for play with 1825 Unit 3.