Shure PG58 switched Vocal Microphone
(compares very favourably to SM58 apart from cost !!)

Shure SM58 legendary vocal microphone
(Industry Standard microphone)

Shure PG58/PG24 UHF radio Microphone system
(10 available frequencies)

Shure SM58/PGX24 switchable UHF radio microphone system
(The Ultimate ?)