Mr. Steam O-Ring Viton For Sight Glass delivers a dependable, leak-tight seal for level indicators in steam showers, boilers, and service panels. Crafted from premium Viton fluoroelastomer, it resists high heat, aggressive cleaning agents, and condensate chemistry while retaining elasticity through repeated thermal cycles. The precise cross-section seats uniformly against glass and metal, helping preserve system pressure, protect adjacent components, and keep sight windows clear for accurate, at-a-glance level checks. Lightweight at 1 lb for easy handling, it installs quickly during routine maintenance or rebuilds and maintains dimensional stability to reduce compression set, hardening, and premature failures. Ideal for both residential and commercial systems, this purpose-built seal supports predictable service intervals and reliable day-to-day operation. Choose Viton construction to extend component life, cut nuisance leaks, and maintain consistent, code-ready performance across demanding steam environments.