Capsules are thin elastic membranes enclosing a liquid core. These objects are used by people fond of spherical geometries to represent cells or artificial objects, used from drug delivery to enzyme containers in fabric softeners. In applications, capsules/cells often negotiate branched networks with junctions thus experience large deformations. In order to gain an understanding of such situations, we investigate a capsule passing through a T-Junction. We investigate experimentally the constant volume-flux viscous flow of buoyancy-neutral thin-walled capsules close to the centreline of rectangular channels, by comparison to near-rigid gelled beads. We quantify the behaviour of capsules in terms of their longitudinal stretching (up to a factor of three without rupture) and show the large range of deformations encountered can be applied to the measurement of the elastic properties of capsules as well as to the geometric-induced sorting and manipulation of capsules.