Hi Joe,
The TL 700 is a super thin skin unit. The hair line is excellent. The beauty of the TL 700 is that it is so easy to attach and remove. Many hair wearers use only 'Got 2 Be Glued Spiking Glue' for a 4-6 day hold--the G2BG washes off with water so cleanup and attachment goes quickly. And you can get it in any density.
The TL 800 is Ultra Lace and there is no finer lace. It is very delicate and therefore can only hold up to 60% density. It's translucent and made of the same material as SFS and French lace. For appearance this stuff is great but the tradeoff is that it is so delicate and you must be careful when you attach and remove. So if your density is greater than 60% this base material is not an option. Up to 60% density this stuff is great.
Regards,
John