Modify horizontal stretch range of model A between 65 cm and 75 cm, adjust model B width from 58 cm to 75 cm to match most mainstream prefabricated household cabinet inner widths.
Shift vertical connecting rod positions to alter total height between 32 cm and 40 cm, make rational use of vertical cabinet empty space to arrange cleaning spray bottles and boxed supplies.
Expand the third adjustable version width from 63 cm to 78 cm, fix depth at 37 cm and height at 28 cm to adapt to ultra wide custom sized under sink cabinets.
Cast main support frame from thickened carbon steel plate to improve compressive bearing capacity, attach silicone anti slip gaskets on four bottom corners to limit sliding during item fetching.
Complete main frame pre assembly before leaving factory, only finish simple locking and fixing steps on site, remind users to measure cabinet inner dimensions before ordering to avoid size mismatch.