I've always questioned the 'hard bonds.' Hair Club does hard bonds also. First they put tape on the perimeter of the unit and then they add a super strong glue called 'Poly Fuse.' It lasts about 6 weeks. Having an attachment last this long without removing it and cleaning the scalp is unsanitary. Your scalp starts to itch. Hair Club used to sell, and maybe they still do sell, a product called 'Alive.' It's a liquid that you pour through the base material and it supposedly dissolves the crud that has accumulated on your scalp over the course of 6 weeks weeks without being removed. It's more comfortable to remove the hair system after about 2 weeks, clean your scalp and then reattach the unit.
John