From CNC Kitchen:

V2 includes an extra M2.5 tip to the sets, where the V1 didn’t have one.

• TS100, TS101Cartridge with M5 Copper Thread

  Compatible with Soldering Irons like Pinecil or Miniware
  (TS101 Soldering Iron affiliate link)

  Easy & Precise Installation
  Installation tips allow quick & accurate installation of short and standard heat set inserts

  Included Tip Size Range
  Brass tips for sizes :
  Metric: M2/M2.5, M3, M4, M5, M6, M8
  (Imperial UN sizes #2-56/#4-40, #6-32, #8-32, 10/24″, 1/4″, 5-16″)

  High Thermal Efficiency
  Copper threads of cartridge provides superior heat transfer for faster insert installation.

  Eco-Friendly Materials