Tech Level (short: TL) is used to denote the relative complexity of an item in Neocron. Often the Tech Level of an item is of importance if you need to Construct, Research, Implant, Recycle, or Repair items. The TL of an item is often equal to the weaponlevel used in a game formulae to calculate requirements and results such as construction time and construction caps, research times, implant times, and the quality of repair jobs.
Furthermore the Tech Level of weapons are generally used to determine their complexity, hence the amount of damage they should be expected to deal, and also the amount of experience you can expect to gain by using a high TL item. The higher the TL of the weapon being used, the more experience it imparts to its user. An item often has as its tech level the level of its main requirement skill you need, like a DEX 80 drone has TL 80.
Tech Levels run from 0 (zero) to 150. A TL-150 item is the highest TL item in the game, though even the top quality, highest requirement items are up to TL 115.
Keep in mind that Tech Levels are sometimes arbitrarily assigned to items without having any real significance, for example an event item that is created when a GM is hosting a quest in the game world.