This perch shelf is similar to the leap-n-ledges you will find at pet stores.  It is approx. 4" x 7.5". Nice size for a chinchilla to perch on, and makes a good "step up" to another level in your cage.
It is pictured without bolts, because we can put bolts either on the short side or on the long side (or both, if you want it as a corner shelf). 
Which side do you want the bolts on? Short side? Long side? Or corner shelf?