There is no extra cost for having the injected--it's the same as the normal V-loop. There is no added thickness to the base. It is the same single layer base. The TL 700 (New Generation base) is just too thin to be injected. The TL 400 is a very popular model--people like the fact that it's so easy to attach and remove. And there is no extra cost for adding a lace front to the unit.
Regards,
John