Only %??? There should be the % on one side and the SG on the other. Also, 25% doesn't even go up to normal salinity for marine animals!
What is the brand and where did you get it?? Not all refracts are made for the hobby, as, mostly they are used for other purposes besides keeping marine tanks.
Hopefully you can return it. 25% is 1.019 SG, so you see that that isn't within the normal ranges that we use for the hobby. My refract reads SG 1.000-1.010, and % 1-100.