This is a felt buffer strip mounted on a foam backed plastic self adhesive strip. The keys come to rest on [ part 170 on schematic ]

 

 

Whilst not an exhaustive list popular models which use this part include :

P35

P70

P85

P95

P105

P115

P125

YDPS30

YDP131

YDP140

YDP142

YDP143

YDP144

YDP145

 

DGX660

DGX650

DGX640

DGX630

DGX620

MM8