THIS IS A USED BUT IN GOOD CONDITION STAINLESS STEEL BASKET, IT BELIEVE IT FITS THE SERIES 500 STRAINER.  THE SIZE IS 8"H X 2 1/2"DIA.  NOT SURE IF IT IS A PERKO OR GROCO. THE BASE HAS A HOLE FOR RESTING ON THE TAB ON THE BOTTOM OF THE STRAINER.  BUYER IS BUYING 'AS IS' CONDITION.