Rugged cylindrical reaction flask with Duran ground flange with o-ring groove, for use with 6517 Quick Release Clamp. Each flask is supplied with one CAPFE (PTFE encapsulated silicone) o-ring. Plain silicone o-rings are also available (see 7855). For reaction heads, see 6528 or 6530. For cooling/heating coils, see 12067.