Those are bog standard TW of the greatest production numbers, the most excellent of all the TW models associated with the TW1 the 1 added when the speaker you have was updated to the TW1a, yours doesn't use the 1. It is just the Time Window, a speaker I have owned since buying new and they are not going anywhere. Sure better speakers may push em aside at times but these are keepers for all they do right. Give em a 9" boost (stand) and set em up, they image like crazy. Handle power without blowing up and sound great. There were a few different upgrades from the first TW to the one you have and yours was made from serial number a couple thousand I guess to close to 50000. Pretty good stuff those speakers.