The soft spout bottle is relatively soft, so when twisting the cap, just tighten it slightly without overdoing it or it might slip. This is not a quality issue! The cap has a built-in washer, so once tightened it won't leak even if turned upside down! The bottle is thin on one side and thick on the other; this is normal and does not affect use or quality! Non-quality issues such as refusal or return require customers to bear return shipping costs if there is damage or missing parts that affect secondary sales!