The Lowepro Lens Case 1S protects a long list of small lenses including the ...
Canon EF 24mm f/2.8 Lens with its hood attached (not reversed)
Canon EF 50mm f/1.8 Lens without its hood
Canon EF 50mm f/1.4 USM Lens without its hood
Canon EF-S 60mm f/2.8 Macro USM Lens Review without its hood
Canon EF Extender 1.4x II
Canon EF Extender 2x II
Canon EF 15mm Fisheye Lens
or a stack of extension tubes, body and lens caps ...
And MANY other similar-sized (mostly prime/non-zoom) lenses.
The Lowepro Lens Case 1S is a very small padded case that offers protection for your lens investment. Water-resistant 600D TXP™ outer fabric provides protection from wear and abrasion.
The Lens Case 1S includes a SlipLock attachment - attach it to your camera bag or Lowepro Light Belt. These cases work very well SlipLocked. Slots are provided to attach one not-provided compression strap.
The interior size of the Lens Case 1S is approximately 3"D x 3.5"H (7.5 x 9 cm).
My $.02 on lens cases ...
Everyone has their own preference for carrying their lenses and gear around. My personal decision has been to individually protect each lens in Lowepro Lens Cases.
My lenses represent a significant investment to me - I take excellent care of them. Acquiring the appropriate lens case for most of my lenses is the standard of storage protection I follow. The lens case investment is small - the protection is very good.
Lowepro Lens Cases are basically thick, slightly-rigid padded nylon pouches with a protective OverLap Zipper(tm) that goes most of the way around the top of the case.
When traveling by vehicle, I often place filled lens cases in a Pelican Case or even a strong Rubbermaid-type plastic storage box. They are well protected from impact and moisture - and the plastic storage container not a target for theft.
When I am carrying the lenses for possible use, I will typically SlipLock a Lowepro Lens Case or two to a Lowepro Toploader case (such as the Lowepro Toploader 75 AW) or a Lowepro Light Belt. This makes for a highly customizable setup. You can adjust your cases to take exactly what you need for the shoot.
Lowepro's SlipLock attachment is a series of flexible and semi-rigid nylon and Velcro tabs. The semi-rigid tab on the Lowepro Lens Case slides through a wide nylon web on a larger case or belt and Velcros back onto the Lowepro Lens Cases. An additional flexible nylon strap Velcros onto the back of the semi-rigid tab locking everything in place.