The capsule is only six millimeters across and eight millimeters long.

这个胶囊只有6毫米宽，8毫米长。

It can range from around two to eight millimeters.

它的范围从大约 2 到 8 毫米不等。

Okay, imagine trying to find a tiny capsule just eight millimeters long and trying to find it on an enormous highway in Australia.

好吧，想象一下，你试图在澳大利亚一条巨大的高速公路上找到一个只有8毫米长的小胶囊。