# How to adjust memoir crop marks line length

I've been searching for the similiar question but still have no luck. I'm following this guide to create crop marks in memoir class and would like to adjust the length of the crop mark lines. Here's my MWE.

\documentclass[showtrims]{memoir}
\setstocksize{216mm}{146mm}
\settrimmedsize{210mm}{140mm}{*}
\settrims{3mm}{3mm}
\setlrmarginsandblock{20mm}{15mm}{*}
\setulmarginsandblock{20mm}{20mm}{*}
% \trimLmarks
\checkandfixthelayout
\usepackage{lipsum}

\begin{document}
\lipsum[1-4]
\end{document}


My questions:

1. Is it possible to adjust the length of crop marks line (\trimXmarks)?
2. If I use \trimLmarks, it creates good crop marks but just too short in my opinion. How to increase the line length?

Thanks.

Update:

I just added the following code under the \checkandfixthelayout line.

\renewcommand*{\trimmark}{%
\begin{picture}(0,0)
\unitlength 5mm % set new length
\thinlines
\put(-2,0){\line(1,0){4}}
\put(0,-2){\line(0,1){4}}
\end{picture}}


... and it answers question no. 1. As with no. 2 (using \trimLmarks), I don't know yet.

...and it works.