Unknown khaki sergeant chevron with odd emblem device in the center

[Siamundo]

I have had this stuck away in a box for several years but have never had an ID for it. Any chance that anyone recognizes this chevron, who and when would have worn it, and what the device is in the center? Thank you for your help.

[Siamundo]

And the back if that helps.

[hardstripe]

It's a Master Sergeant in one of the South or Central American countries. If I remember correctly, it may be El Salvador.