I need some window keepers. Please take a look at a window keeper video I put on youtube, seen below. It looks very close to your 90-257. There is no measurement on your product page showing the width of this item (90-257)or the opening that the latch goes into. Also, it is very important that the two mounting hole with the 7/16 centers are small, since two screws must catch into these holes to secure the keeper.
Thanks
Brent
[video unavailable]