below like reference numerals in fig1 10 refer to like structure and therefore additional description with respect to fig7 10 is not necessary like reference numerals in fig7 10 having prime marks u2032 refer to analogous elements as shown and described in connection with fig1 6 but having differences that are either apparent by reviewing the drawings themselves or by a combination of reviewing the drawings and the additional description contained below the primary difference between assembly 10 and assembly 10 u2032 is with respect to the lids 12 a 12 a u2032 and the manner that the lids 12 a 12 a u2032 connect with the bodies 12 b 12 b u2032 of the cassettes 12 12 u2032 in the first embodiment the lid 12 a is held down to the body 12 b by a series of snap fit connectors 13 on each of the four sides of the cassette body 12 b these connectors 13 engage an outer flange section 15 of the lid 12 a thus the user typically would use his or her finger to depress each of the four sides of the cassette lid 12 a downward to engage each of the sets of snap fit connectors 13 the cassette 12 u2032 shown in fig7 10 instead uses a circular lid 12 a u2032 having three connecting elements 60 spaced apart by 120 u00b0 elements 60 connect in a snap fit manner with connectors 62 on.