The Marquis Silk & Steel MA130S (formerly M1400) acoustic guitar strings from Martin are made with tin-plated steel core wire and silver-plated copper compound wrap wire.
Martin wraps the ball ends with soft silk to prevent wear on the bridge and end plate of your guitar.
| Note | Gauge (in.) | Material |
| E/1st | .0115 | Plain steel |
| B/2nd | .014 | Plain steel |
| G/3rd | .023 | Silver-plated copper |
| D/4th | .028 | Silver-plated copper |
| A/5th | .038 | Silver-plated copper |
| E/6th | .047 | Silver-plated copper |