Embodiments of the invention provide devices and associated methods for use when performing endoscopic procedures. According to one aspect, a sheath positionable within a working channel of an endoscopic device, and adapted for receiving one or more instruments, is provided. The sheath can include a first channel and a second channel, the first channel and the second channel extending at least partially along a length of the sheath, wherein at least one of the first channel or the second channel includes an open edge open along at least part of the length of the respective channel.