Its protective insulation sheet. You need to rap this sheet all over your lithium battery after complete making. Mainly over the spot poart. on the nickel strip. Then this insulation paper will protect the nckel strip from futher damage and protect the inner battery. it can resist the fire some limit and protect the battery.
Its One roll with 1 meter length and 65 mm width. Its adhesive and sticker type Tape. colour is Green.