Genuine Mercedes rubber plug/buffer 10mm - 110 987 00 39, 1109870039 used in various locations across many models.
Often used as a blanking plug for the windscreen washer reservoirs on many models.
Blanking plug on your washer bottle crumbling away or is missing completely? 10mm 
Rubber plug split or is falling out and needs replacing?
This part suits vehicles most Mercedes Benz models manufactured between 1968 and 2012 including the following MB Cars:-
W107 SL            (1970 to 1989)
W107 SLC         (1972 to 1981)
W114 Sedan      (1968 to 1976)
W114 Coupe      (1968 to 1976)
W115 Sedan      (1968 to 1976)
W116 Sedan      (1973 to 1980)
W123 Sedan      (1976 to 1985)
W123 Wagon     (1975 to 1985)
W123 Coupe      (1976 to 1985)
W124 Sedan      (1984 to 1996)
W124 Wagon     (1984 to 1996)
W124 Coupe      (1986 to 1996)
W126 Sedan      (1979 to 1992)
W126 Coupe      (1979 to 1992)
W140 Sedan      (1990 to 1998)
R170 SLK          (1996 to 2000)
R171 SLK          (2001 to 2010)
W199 SLR         (2007 to 2010)         
W203 Sedan      (2001 to 2007)
W209 CLK Cpe  (2002 to 2010)
W210 Sedan      (1996 to 2002)
W220 Sedan      (1998 to 2005)
R230 SL             (2001 to 2011)
W461 G-Wagon (1991 to date)
W463 G-Wagon (1990 to date)
W639 Vito          (2003 to 2014)
Unimog U1700L (1975 to 1993)
May suit other models. 
 
This part is shown as no 74 in the diagram above
 
Original Part No:- 
A1109870039
1109870039
A110 987 00 39
110 987 00 39
110 987 0039
110-987-00-39
Superseded by 000 997 33 20
 
Don’t not pay over $7.50 for a genuine part. Our price only $4.00
NB:- this item is advertised on other sites and may be sold without notice.
 
Please check you have the correct part number for your vehicle.
 
Most parts available for all Classic Benz’s, G-Wagons, W170, W171, W220, W230, W240, Vito and Viano Mercedes models.
 
McStarparts – “Keeping classic Benz’s on the road.”