[JSeery]

Never heard of stat-o-seal so I looked them up:

Introduction
Most fluid systems have fasteners that must be sealed. Parker’s fastener seal designs found in the Stat-O-Seals® and ThredSeals® feature an elastomeric sealing element molded in place within a metal retainer (washer). Although resembling a simple o-ring groove concept, the mold in place fastener seal offers numerous advantages. Ideal for sealing small and miniature sizes, the Parker Lock-OSeal® is a two-piece combination seal comprising a separately molded o-ring fitted within a surrounding metal washer. Other speciality fastener seals are also available.

Stat-O-Seals
• Intended to seal the shank of a bolt immediately under the head
• 600 Series: Intended for sealing standard series fasteners
• NAS1523 Series: Applications that require conformance to NAS1523
• 610 Series: Intended for sealing metric fasteners from 5mm to 22mm
ThredSeals
• Intended for sealing directly on the fastener threads
• 750 Series: Intended for sealing most UNC and UNF threads
Lock-O-Seals
• 800 Series: Intended to seal the shank of a bolt immediately under the head
• Ideal for sealing small and miniature sizes
• Special material combinations not available as a 600 Series Stat-O-Seal
Specialty Products
• Fastener seal kits
• 250 Lock-O-Seals for sealing straight tube fittings and banjo style fittings
• Food, beverage and FDA related applications
• Custom designed fastener and fitting seals