I am new to the hobby and am currently running 2 ovals (O-72 & O - 63 curve) on an 8 x 12 area. I currently don't have any turnouts on my layout. Over the next year I am planning on upgrading my layout space and have been playing around with layout ideas for this new space. I had a few questions about turnouts. What does a #5 and #7.5 turnout mean and when would you use them in a layout? Also if you were running two main lines on your layout and you wanted to have a cross over between them which type of turnout would you commonly use? I currently use Atlas O track. Thank you in advance for your reply.