Size comes before color
Most guys shopping for their first hairpiece start with color. Then density. Then maybe base material. Size comes last, if it comes up at all.
It should be first.
Color and density decide how it looks. Size decides whether you can wear it. Get the shade perfect and the density right on a base that doesn't fit your bald area, and you end up with edges that lift, heat trapped against your scalp, and a piece you're aware of all day instead of one you forget about.

Why universal sizes are a compromise
The standard panel sizes you see online are deliberately bigger than most men need. That isn't an accident. A large panel can be trimmed down to fit almost anyone, which is convenient for a seller shipping to customers they'll never meet in person.
It works fine if your hair loss is extensive. If it isn't, you're wearing a base over skin that still grows hair. That skin doesn't breathe. Sweat collects under the material, the whole thing gets heavier and hotter than it has to be, and the edges sit further out, where there's less hair to blend them into and more chance they lift.
A receding hairline, a thinning crown, one small bald spot: that's the stage where universal sizing does the most damage.
What a smaller base changes
A small base covers the area that's actually thin or bald and stops there. The edges land where your own hair still is, so there's something to blend into and no line to hide.
Less material against the scalp means less heat and less sweat. It's lighter. It moves the way your scalp moves instead of sitting on top of it.
And it stays down. Bigger isn't more secure, which is the assumption most first-time buyers make. Less surface area means less adhesive doing the work and fewer edges with nothing holding them.
What we stock
Small sizes are standard stock for us, not a special order: 5x7, 6x8, 6x9, 7x9, and 7x10, shipping from our US warehouse in 3 to 5 days.
8x11, 9x11, and anything else custom is cut to order. Give us the dimensions and we'll make it.
You shouldn't have to buy a universal panel and hope it works out.
The rest of it
Base material comes down to how you wear your hair and how much airflow you want. Lace breathes best, thin skin gives the closest blend at the hairline, and a hybrid puts thin skin at the front with lace through the rest. Color and density are customizable too, across a wide range of shades and a full inventory of human hair.
So the piece you get isn't a close match to your head. It's built for it.
Working out your size
Measure what's actually gone. Not what you expect to lose in a few years, not what you'd like covered for a fuller look. The area that's thin or bald today.
Length front to back, width temple to temple. That's your base size.
If you land between two sizes, take the smaller one. A base that stops just short and blends into your own hair will always look better than one that runs past your hairline with an edge you have to hide.