TPM-1 and 2 have both been upgraded. TPM-2A4 will include improved agility thanks to improvements in the control software and the option of a two-stage warhead (two warheads basically) to help counter some enemy tactics where a less important part of a ship is "sacrificed" to be destroyed by a TPM warhead to allow the rest of the ship to survive. There are also a number of software fixes. Production will switch to A4 next week.
TPM-1D6 is a new version of the TPM-1 but will only be an upgrade to refurbished older missiles as production has now stopped. It includes the warhead option and some software fixes.
