What are the main differences between the 2 Interface unit Models?

[HuBaroth]

Hi there,
Not sure if that question has been answered before, but does anyone know what differences there are between the 2 sets of Interface Units ( you know the 'suitcase' thing). From what I read, the IFU 30 was the one you bought separately, you had to get the Cdrom2 (CDR-30) by itself.
Apparently, the IFU-30A and CDR-30A came as a combo in one box.

Thing is, I have noticed some hardware differences too. The IFU-30 and CDR-30 are missing some little features that the IFU-30A and CDR-30A have.
The features (for the IFU-30a/CDR-30A) are in the case of the interface unit: 2 little metal 'points' that are located on the CDRom side, and the CDR-30A has a metal plate underneath (that touches/sits) just on the metal bits in the interface units.
Does anyone knows what they do or are for? At the moment I'm using a CD30A with the IFU-30 interface unit (so it does not have the 2 bits that touches the cdr rom metal part), I have another interface unit (a IFU-30A) but it's in storage at my parent's house so cannot test to see if it makes any differences....

I would appreciate any info regarding those hardware differences. 

[Arkhan Asylum]

A stands for awesome.

[Tatsujin]

This was a grounding improvement which was added to the 30A.
It doesn't do much, nothing you will ever notice.
Was probably a simple EMC precaution.

[HuBaroth]

Thanks for the heads up Tatsujin, I thought that it might have been the case, but thought that It could affect some functions of the CD-Rom-Rom.
Cheers 

[SuperPlay]

Interestingly the core grafx has similar points, that are missing from the original PCE

Apologies for pic quality this was taken with my phone

/tgxl.jpg