From it's introduction in 1958 the M-20 (and it's slightly bigger brother the M-30) had been finished with a matt (usually brown) finish but during 1969 the M-20 became available with a 'gloss finish' as an option for $ 10.00 extra.
This example has the optional Cherry Red finish. It also has the optional 'electronics' package installed that was introduced during the second half of the '60s and was available on any steel string acoustic for an additional $ 50.00. It's a regular magnetic pickup with standard vol. & tone controls mounted on the top and if you wonder how it sounds plugged in, I can tell you that it sounds as awfull as a Gibson J-160E, which had a similar setup.
Acoustically this guitar is a gem and in spite of the electronics it's my favorite M-20. Also note the wood veneer peghead overlay with the silkscreened logo, which was introduced around this time.