When a Channel is serving transfer to a renSime so that the renSime does not have to turn to a Gen for his or her Selyn. Gender plays no part in Sime to Sime transfer. The two Sime place their hands along each other arms as in a Gen to Sime transfer and their handling tentacles entwine to keep their arms stable and the tiny lateral tentacles from the side of each Simes wrists emerge to coil around the others' laterals and the fifth contact is made and transfer is completed. One Sime is always a channel, although before Unity, there were cases where renSimes have attacked other renSimes due to desperation because no Gen was available.
Channels would sometimes travel from Householding to Householding carrying extra selyn, and use channel-to-channel tranfer to deliver selyn to the Householding that was lacking.
This practice of ferrying selyn around during an emergency became the basis of the Modern Tecton practice of gathering selyn out-Territory from volunteer donors and bringing it in-Territory using a channel as courier. A channel courier would be able to deliver "living" selyn that another channel could distribute in a way that satisfies non-junct renSime Need. Batteries can not replace these couriers as the selyn deposited into a battery loses that "living" quality.