Zilla Non-Locking Screen Clips firmly secure covers to prevent escapes. Spring steel snaps free for easy user access and installs in seconds. Assured security for valuable reptiles; a pet wouldnt think of escaping with Zilla Cage Screen Clips on the job!Firmly secures terrarium coversPrevents inhabitants from escapingKeeps screen covers securely in placeEach package contains 2 screen clipsEach clip firmly secures a corner of the screen to the terrarium rim without the use of extra hardware or complex installation. Simply slip the top of the clip into the top molding of the cover, then snap the clips bottom between the glass and the terrarium frame. Press down and pull out to free the clip and open the lid.Small Clips: 4"L x 0.1"W x 5.3"H - Fits 5 to 29 Gallon CagesLarge Clips: 4"L x 1"W x 5"H - Fits 30+ Gallon Cages