Here is a pair of very usable casement window hardware.  One side is screwed to the frame and the other end to the

window.  It allows you to hold them open exactly where you want them.   Made of heavy, solid steel with a brass tone gilt

finish, the bar on each is 12 1/2" long.  This price is for one pair.  There are two additional pairs available and shown in

the photos with discounts on both price and shipping if you buy more than one pair.