I myself can't really comment on what s/a tape used to be but as an airfield electrician i carry out jointing underground also, with kits that previously incorperated uninsulated barrel crimps a patch of s/a and an outer heat shrink to through joint the 6mm2 double insulated cables used on airfields through out the country.In the last 3 years for some reason have done away with the s/a patch and included a small inner heat shrink!!!!
i don't know why this is but personaly i would prefare the patch, inner and outer heat shrink [Linked Image]