Replying to Marker King Pin Brake Size Question

Hola NS,

Quick question: I'm in the Market for some Kingpins and recently got a gift card to Amazon, so I went on to see how much they are and found them for quite cheap! I found them in size 100-125mm which I imagine is the brake size but it doesnt specify for as low as ~$550 but when I look up prices for size 75-100mm they are ~$450!

I'd be putting them on some Salomon QST 106's so I would need the 100-125mm size brakes. My question is can't I just but the 75-100mm brakes and just change the brakes out for some larger ones and save $100?

Here's the link for the page: https://www.amazon.com/Marker-Kingpin-13-Binding-100-125mm/dp/B01DHC9JAO/ref=sr_1_1?ie=UTF8&qid=1481778308&sr=8-1&keywords=marker%2Bkingpin&th=1&psc=1

You can see the price changes just by changing the size.

Thanks in advance for you help!