It is probably me been dumb but i keep seeing things like this Vintage Durham Duplex Straight/Safety Razor *Free USA* | eBay
Some are listed as straight razors. What are they exactly, are they just a straight with a guard attached ? how are they used ? does that guard come off so you can use it as a regular straight razor ?
When i first saw them i thought they were for trimming head hair but i dont think that is the case.