Can you please explain your comment circa 1900 when by law all German Silver had to carry the crescent moon and crown mark from 1888 and was usual from 1836 my research suggest the piece was made earlier

Are there any other marks? If this were made in the 19th century, it would have city and maker hallmarks. I have not found Knapp & Schlesinger to be operating earlier than 1900.

on this auction site From a Dusseldorf aution house Hargesheimer
https://www.kunstauktionen-duesseldorf.de/index.php?cPath=6942_6947&page=2
you will see lot 1334
Auction: 79-IV
BIEDERMEIER-SPARDOSE, FUßTABLETT UND ZWEI SCHÖPFKELLEN
Hamburg, Knapp & Schlesinger, 1828-1851 (Spardose) / Breslau, Leberecht Fournier (1821-1849), 1822-1834 (Fußtablett)

Title:

BIEDERMEIER-SPARDOSE, FUßTABLETT UND ZWEI SCHÖPFKELLEN

There are no other marks on the piece

due to the rarity of such pieces in solid silver from mid 1900s I don't understand your low evaluation

The KNAPP & SCHLESINGER mark on your silver is the one used by the company from about 1900 on. I do not know why there are no other marks when there should be, which is of some concern to me.
Here is the comparable I used in my valuation:
https://www.bidsquare.com/online-auctions/leslie-hindman/silver-creamer-and-sugar-knapp-schlesinger-length-of-tray-11-inches-1112830.

Taking the weight of the piece and calculating it to the current price of silver, I get a price of just less than $600; accounting for buyers premiums and other auction house fees, the most likely estimate on this would be $300-500, possibly $400-600. If you want me to change it to $400-600 I would do that but I do not think this is early than the date of 1900 as originally stated.

ok thank you I appreciate if you would do that
thank you

Done!