equivalent of a sql query in posgresql

SELECT products.product_name, products.units_in_stock
FROM products
WHERE products.units_in_stock = (
    SELECT max(products.units_in_stock)
    FROM products
    WHERE products.units_in_stock > 30
);

SELECT products.product_name, products.units_in_stock
FROM products
WHERE products.units_in_stock = (
    SELECT max(products.units_in_stock)
    FROM products
    WHERE products.units_in_stock > 30
);