Battle Rewards crates may contain components of up to four items. The number and type of components you can receive is chosen randomly within a range you can see on a components icon:
1700-5.3K here means that you will get at least 1,700 components in total. These may be different items' components: for instance, you can receive many components of one item or fewer of each item.
When in a crate there are components of several items, you can notice that each type has a 0 - 1700/5300/4500 range as in the screenshot below, which shows the maximum amount of components of each item you can get, but the overall amount of components received won't exceed 5.300.
