Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_53846 ( "Species" text, "Strain" text, "Type" text, "Base Pairs" real, "Genes" real )

### Question ###
What is the largest base pair with a Strain of unspecified?

### Accurate SQL ###

SELECT MAX("Base Pairs") FROM table_53846 WHERE "Strain" = 'unspecified'