stat-o-seals

Advantages:
No machined O-ring grooves are required in the mating flange
Precisely controlled optimum percent squeeze eliminates over compression
The retainer edge is visible after installation allowing for easy visual inspection and reducing
   failures caused by missing seals
The ridged self centering design provides easy and accurate placement of the seal
The solid metal to metal contact improves joint stability and eliminates re-torquing
Long reliable service and a high level of reusability
Rubber/bolt interference provides for easy assembly

Stat-O-Seals are one-piece, molded-in-place seals with the rubber sealing element mechanically and/or chemically bonded to the metal retainer. Parkers Splined and Coined mechanically bonding feature is used on many 600, NAS1523 and 610 series sizes. This feature ensures a positive attachment of the rubber to the retainer, eliminating missing or loose seal elements associated with bonded seals. Stat-O-Seals are designed to seal beneath the head of the fastener as shown for both internal and external pressure and vacuum systems. Stat-O-Seals offer users long and reliable service, a high degree of reusability and easy assembly.
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