Adams 1099 Envelopes are security-tinted for privacy & sized for a precise fit with tax forms with three forms per sheet like the 1099-NEC. Durable, gummed closure provides an aggressive seal. Complex security tint conceals the appearance of letters & numbers, even when held to light. Perfectly aligned double windows keep personally identifiable information out of view. Envelopes are designed to fit 1099-NEC tax forms.