the sc2 spares carrier is larger than the other sc1 spares carrier that I have. It is longer to accomodate the longer lamp in the middle. The plastic is a very high quality, I can say this because I removed one of the lanyard hooks on the case and the plastic was very very abrasion/impact/distortion resistant. The snug fit between the top and bottom portions combined with the rubber O-ring creates a watertight/airtight seal. Very nice product from surefire... If you only want to carry batteries, get the SC1 as it is less bulky.
Pros: very very dyrable, impact resistant plastic
Cons: little pricey
This review was written in the old system and had content requirements that are different than reviews written today.