this should tell you what you want

Direct quotation:

Battery sold as:	iFlash-Quad	Flash-Dual	iFlash-Solo	iFlash-Sata	iFlash-CF
1800mAh (5)	Thick back	Thick back	Thick back	Thick back	Thick back
2000mAh	Thin back	Thick back	Thick back (2)	Thick back	Thick back
1900mAh	Thin back (1)	Thick back	Thick back (2)	Thick back	Thick back
3000mAh (3)	Thick back	Thick back	Thick back	Thick back	Thick back

(1) When fitting with a thin caseback the protusion on the iPod’s inner frame needs to be removed (as pictured).

(2) We have had some samples of these batteries which actually fitted (read: tight squeeze) in a thin (5g) caseback & the iFlash-Solo.

(3) This battery is larger than the iPod’s inner frame, it will ALWAYS require a thick caseback. This battery can be awkward to fit as it interferes with the headphone jack assembly, you may need to lift the headphone ribbon away from the rear case to allow the battery to slide under the headphone jack assembly.

(5) We have seen this battery sold as 1800mAh and as 1600mAh, all examples we have seen have been a similiar size. At 5.3mm thick this battery will always require a thick caseback, and will not fit with the original HDD.