WordPress at a glance
filter is not described

wp_get_attachment_thumb_url filter-hook . WP 2.1.0

Filters the attachment thumbnail URL.

Usage

add_filter( 'wp_get_attachment_thumb_url', 'filter_function_name_7093', 10, 2 );
function filter_function_name_7093( $url, $post_id ){
	// filter...

	return $url;
}
$url(string)
URL for the attachment thumbnail.
$post_id(int)
Attachment ID.

Where the hook is called

wp_get_attachment_thumb_url()
wp-includes/post.php 5467
return apply_filters( 'wp_get_attachment_thumb_url', $url, $post->ID );

Where the hook is used (in WP core)

Does not used.