The RLN5878 has been discontinued.
The replacement part is the Motorola PMLN6125a.
Receive Only Surveillance Kit, Black (single wire) Intrinsically Safe (FM)
Motorola often changes the product SKU name. This product may have also been known as RLN5878a, RLN5878b, RLN5878c, RLN5878d, RLN5878e, RLN5878f, RLN5878ar.