Booster pack.
Just bought 2 of these.
One for Me & one for my Grand Daughter.
https://www.amazon.co.uk/gp/aw/d/B015TKUPIC?pd_rd_plhdr=t&hsa_cr_id=0&qid=1791283025&sr=1-1-941ebe59-d25b-49d0-b214-12cc5b66c90f&i=aps&aref=FvAI0FLsZH&_encoding=UTF8&ref_=sbx_s_sparkle_sbtcd_asin_0_img&pd_rd_w=tBxBv&content-id=amzn1.sym.c8974dda-a96b-4856-ba25-1e9ee05c8882%3Aamzn1.sym.c8974dda-a96b-4856-ba25-1e9ee05c8882&pf_rd_p=c8974dda-a96b-4856-ba25-1e9ee05c8882&pf_rd_r=8E83GVC75BVEM708CYF7&pd_rd_wg=Ubjxg&pd_rd_r=f72f9fbf-6622-4b0a-a68c-8fbf29fd4e16
They just arrived and look like a Very good product.
Lithium Ion so much safer than Lithium Polymer.