Mechanical seal H7N is wave spring design and can replace BURGMANN H7N.
Mechanical seal H75 is multiple spring design and can replace BURGMANN H75 and MTU DR1-HS.

Mechanical seal M7N is wave spring design and can replace BURGMANN M7N, Flowserve Europac 600 seal and Sterling 270 seal; It is used for Bornemann pumps. 
Mechanical seal M74 is multiple spring design and can replace BURGMANN M74. 
Mechanical seal M74F has pumping ring and is used for higher pressure. 

All these seals can be double seals, tandem design or back to back design. 
Mechanical seal M74D is a double seal. 

M7N and M7G49 can be used for KSB Etanorm pumps and double mechanical seals, back to back arrangement. 

MECHANICAL SEAL inboard 030-R(433.01)       MECHANICAL  SEAL outboard 030-R(433.02)
KU028S.M7G49                                                           KU028S/M7N
KU038S/M7G49                                                           KU038S/M7N
KU048S/M7G49                                                           KU048S/M7N 

MG13/RMG13, HJ92N/HJ977, and M7N can be used for Grundfos pump model B, NB, 50/60HZ.

pictures of M7N-45mm and you could see the nice quality.