GE 278B-1110 Category : GEThis is the non-addressable version of the EST SIGA-278. This particular unit is branded by GE.
GE 521BXT Category : GEI think that this smoke detector might be intended for use in security systems.
GE/EST SIGA-278 Category : EST/Edwards, GEThe metal components on this pull are a bit rusty. It is co-branded by GE and EST.