Us,3 Cent , George Washington, Stamp- Different Perforations?

Could somone please give me some more information about
this US 3 cent George Washington stamp. The perforations are slightly different- 10 ¾ at top and bottom and 11 at left and right sides. Shouldn't all sides have a perforation 11 ?
The other features that puzzled me is the trades which are showing at the paper and the ribbing of the back. I hope you could help.

1) I am not seeing 10.5
2 Perforation rates are rounded to the closest value in Scott
3) it usually pays to use an actual commercial perforation gauge rather than one printed on a piece of paper

I'm sorry if the perforation guide I'm currently using is not very precise but this is the only one I could find and afford. I bought it from a Bulgarian Posts specialized philatelical shop.
It is manufactured in Germany,they told me that this the best they have in stock.
If the measurements should be corrected to the closest perforations what should it be , 11 or 10½ ?
And what could say about the fibers in the paper ,are they just a normal part of the paper ?

Your gauge is fine.
No U.S. stamp will gauge exactly 10 or 11 or 12 or 10.5
The catalog rounds to the nearest 0.5, so one must pick the closest value.
In this case it is perf 11
Your stamp is one of the "offset" printings, Scott 529 or 530.

If you post a photo of just the gauge, it would help people to understand. With the close up photos some may assume it is an internet printed or photocopied gauge.

Yes, US stamps are just gauged in half steps. So you must pick the closest fit, not go by the exact gauge.

A caveat: some catalogue publishers like Stanley Gibbons, Michel, or Yvert & Tellier may have a different policy and round to the nearest quarter. Always check the introductory notes to your catalogue for the policy on perforation gauges.

The reason I questioned the gauge is because I cannot recall ever seeing a commercial gauge that was constructed of paper which is a hydrophobic material that expands and shrinks as the moisture content changes. I assumed that it was printed on a home/office printer as well which hardly screams "accuracy".

I also said in the very first response to the OP's post:

OP is from Bulgaria. I think most collectors of international stamps there will use Michel. If you are not familiar with Scott but with Michel, you might be prone to interpret 'closest value' as nearest quarter, even when looking at stamp smarter.

@post_pe, what catalogue do you use? Do you have a Scott catalogue?
Your post suggests you were looking at some listing. It always helps if you state what your reference is.

I'm sorry for not been accurate ,I should have mentioned that in my first post. It is made by thin pice of iron or some other aloy whith the guide printed directly on it. Unfortunately there is little assortment of philatelical products and supplies which you could buy in our country.
The market of such type of product is very limited in Bulgaria.
At least now I can be sure that correct perforation is 11,thanks again for the help of all participants in the discussion.
NSK you have made a correct observation by saying that I might be using Michel catalogs. Mine are from 2002 issue, a bit old but there are still helpful . The information which I was referring also comes from Michel.
I have only one book of Scott catalog I currently use it but it's not for US stamps.
Most the philatelists from our local club and other colleges I know, use Michel and some say they are not even familiar whith Scott catalog at all. That's probably because unlike other European countries we didn't had much contact with the literature published abroad .

Sorry about the image but I couldn't find a better .
This is image of it which I took from the only one online shop I could find selling it.

Scott is hardly used in Europe.

Most European countries have their own catalogues.

Collectors of foreign stamps use one of three catalogues: Stanley Gibbons (primarily UK and Irish Republic, although Ireland has a strong German following that uses Michel, as well as those who collect GB & Empire & Commonwealth), Yvert & Tellier (France, Belgium, Spain, Italy, and to some extend my own country, as well as those who collect France and colonies), or Michel (other European countries, and more recently also my own country, as well as those who collect Germany and colonies and occupied territories).

It makes sense you use Michel. Most European sellers will use that, or Yvert & Tellier.

The first time I visited Bulgaria (1980), it was easier to speak German than English, if anyone spoke a foreign language at all. When I returned in 2016, English had become the most common foreign language. But that second time, I visited inland towns.

I stand corrected on the gauge. It sure did look like paper. Good!

Yes, I also tink that Scott is not so frequently used . In past decades ( I mean in 1970s and 1980s)Yvert was often preferred by Bulgarian philatelist. Our local club didn't owned other catalog for foreign stamps different from Yvert before 1990. French language and culture was very popular back then, maybe this is the reason for purchasing this issues. Of course German was also a very popular language. There were many German speaking tourists why visited our country in this period and the people who worked at the tourist branch had to know German language in order to communicate freely with them. The only words on English which most of the people understood back then were whisky, Marlboro and Nescafe. Now everyone speaks English and very few speak German or other language.

The structure resembles paper material, but it is probably because I took the images at a very close distance.