Straight-edge razor help?

ive been watching a lot of videos about straight edge razors and ive been wanting to buy one which i will do when i get my money in but what i want to ask is some of the razors ive looked at the blade comes out to replace by another one are all the straight-edge razors like that or is that only specific ones because i thought the blade was just solid metal and the blade didnt have to be replaced just needed to be sharpened so any help with that would be great thanks