I have a Madbull, G&G, and Krytac HopUp set ups with a variety of different size barrels for your to choose one that works best with what you need it for. The madbull and G&G are flat hoped and the Krytac is standers to how it comes. I also have O rings and Teflon tape to add on to make sure you get the best air seal and fit for better results. $35 each, and I’ll cover shipping and fees. I’m also open to trades