WordPress at a glance
function is not described

wp_get_attachment_thumb_file() WP 2.1.0

Retrieve thumbnail for an attachment.

Hooks in function
Return

String/false. False on failure. Thumbnail file path on success.

Usage

wp_get_attachment_thumb_file( $post_id );
$post_id(int)
Attachment ID.
Default: 0

Code of wp get attachment thumb file: wp-includes/post.php VER 5.1.1

<?php
function wp_get_attachment_thumb_file( $post_id = 0 ) {
	$post_id = (int) $post_id;
	if ( ! $post = get_post( $post_id ) ) {
		return false;
	}
	if ( ! is_array( $imagedata = wp_get_attachment_metadata( $post->ID ) ) ) {
		return false;
	}

	$file = get_attached_file( $post->ID );

	if ( ! empty( $imagedata['thumb'] ) && ( $thumbfile = str_replace( basename( $file ), $imagedata['thumb'], $file ) ) && file_exists( $thumbfile ) ) {
		/**
		 * Filters the attachment thumbnail file path.
		 *
		 * @since 2.1.0
		 *
		 * @param string $thumbfile File path to the attachment thumbnail.
		 * @param int    $post_id   Attachment ID.
		 */
		return apply_filters( 'wp_get_attachment_thumb_file', $thumbfile, $post->ID );
	}
	return false;
}