A 3.4 oz pump spray of 100% DEET.

For trips where the insects are the defining feature of the day — standing water, humidity, dusk, no wind.

Higher concentration does not repel harder, it repels longer. 30% covers an evening comfortably; 100% is for all-day exposure or genuinely bad conditions.

Apply to exposed skin only. Do not apply under clothing, and wash it off when you are back indoors for the night.

One warning worth knowing: DEET attacks plastics and synthetics. It will haze a watch crystal, cloud sunglasses, soften a rain jacket's coating and weaken fishing line. Spray it on your hands away from your gear, and wash your hands before you handle anything you care about. At 100% concentration this matters more, not less.