you have been spoon fed repeatedly already and still can't chew it.. are we going to have to do chewing for you too?
the rules on this site state that information regarding the sale of unregulated firearms (airsoft guns shooting over 366 FPS with a .20g BB) is prohibited for persons under the age of 18.
there is a system in place on this site that lets you verify that you are at least the age of majority (18 or over). it involves meeting an "age verification representative" in person (face to face), so that documentation proving your legal age can be physically viewed and confirmed authentic.
outside of this site, you are free to do as you please. this site has an extensive buy&sell section where you can purchase any gun, accessories and equipment from either members who post such items for sale, or direct access to vendors. which you will only get access to if you are age verified.
as to your confusion.
the glock on the 007 site is considered an unregulated firearm (even though it shoots less than 366 FPS on a .20g BB) because the receiver (frame) is a transparent material. if it were opaque and shoots under 366 FPS, then it would be classified as a replica (prohibited) firearm.
fully black guns sold on other sites will all shoot above 366 FPS as per importation regulations. again, the only exception to have them shoot lower is if the controlled parts of the firearm (receiver) is transparent.
hope this clears things up for you.
Weapons Technician / Gunsmith
Don't look at me, I don't know, lol ¯\(°_o)/¯.