保温ボトルスリーブ

My flask has taken a few solid knocks on the train and the sleeve's taken every one without a mark, plus my coffee's stayed noticeably warmer than before. Honestly, it’s exactly what I needed for daily commutes.

The insulation layer actually does its job — my coffee stayed warm for a full hour longer than without it on a chilly morning walk. The sleeve fits snugly over my flask and the padding gives me peace of mind when I toss it in my bag.

Dropped it off my bike rack onto concrete and the flask didn't get a single dent, plus my coffee stayed hot through my whole morning shift. The sleeve fits snugly without being a struggle to slide on, which was my main worry.