This 6" wood shelf is 6" long and made of 8" wood, so it measures approximtely 6" x 7.5".  Good size for a chin to chill on. 
Would you like a hole in your shelf?  Be sure to select that listing as well and add it to your cart! 
Picture coming soon... bolts can be installed however you want -- long side, short side, one long & one short, and so on...
Which side do you want the bolts on? Short side? Long side? Both? Custom?