I'm thinking of purchasing a unit from Toplace and had a question about bases. Before the question, as background I've been wearing hair for 20 years and switched from the "clubs" to directly purchasing from Hair Direct about 4 or 5 years ago. The question about which base to order is due to some issues I have with the current units I order. I usually order a lace unit with a skin perimeter and for some reason I have varying success with the ability of the perimeter of the unit to lay flat to the scalp. Sometimes the perimeter lays flat and sometimes I get "ridges". When the unit lays flat it is very easy to attach - even red liner tape will give me a pretty good hair line. However when the unit is creating ridges, almost nothing I do gives me a good hair line (ie. I get "ridges" all along the hair line). I"m not sure why this is and especially why sometimes one unit works and another doesn't. Is there something I need to know about the bases? Thanks for the help.