Unbottle is what superhero stuff are made off— Steel, Stainless Steel. High-grade 18/8 stainless steel on both the inside and outside, this is a chromium-nickel-iron alloy (18% chromium & 8% nickel).

Since the Unbottle Bottle is made from stainless steel, technically the bottle is rust- free if used properly— like dried out fully before use, cleaned and stored properly. 

No - All Bottles by default come with a stainless steel lid excluding Chrome/Rose Gold, All Mono Black, All Mono White and All Mate Bottle, which come with a matching colour lid. You can buy spare lids separately.