It is the 4 upgrade vouchers and the soft landing should you not requalify for Elite plus. That seems a bargain for 350 $ at first sight - for less than 100$ per one-way an upgrade! But...of course only if you expect to fly TK regularly in the next years, and you expect TK Y flights for which you can use the upgrades. If your company already structurally pays J, the upgrade vouchers may be less of a benefit?