The Tilers & Trade Shop's Levelling System is a two (2) part system.  The clips (1000 per box), are one part of the 2-part installation system, engineered to hold in a true plane, align, space, and hold large body procelain tile, marble and stone during the drying process of the adhesive.  This part of the system works by surface aligning and spacing tiles.  The wedge part of the system (sold separately in a 250 box), works by maintaining tiles at an even height until the adhesive sets, thereby ensuring the resulting surface is level and free of lippage as far as practicable.