This square Teflon (PTFE) dipper device is used to aid in the etching process for 4″ silicon disks. The dimensions of this dipper are 4.35″ x 4.35″ x .5″ OD (4.10″ x 4.10″ID).  This will hold a wafer with a 4.00″ OD diameter and can be used with a 7″ container.