These are our own design for our frag plugs.  They will not work with any other frag plugs.  They are designed to screw into our SPS, LPS and Softy Frag Plugs.  They are also designed to lock into your egg crate so fish don't tip over the plugs.  Your Frag Plugs will stay in place on your egg crate.
 
We sell these at a pack of 12.