Siemens SIPART PS2 6DR5 Series Compact Operating Instructions page 88

Accessory part sealing plug / thread adapter
B.4 Dimensional drawings of accessory part
Thread adapter Ex d, M25 x 1.5 on M20 x 1.5 and
M25 x 1.5 on ½-14 NPT, dimensions in mm
Sealing plug Ex d ½ -14 NPT
88
①
Sealing ring: Use for dust protection "Ex t" type
of protection.
Compact Operating Instructions, 09/2019, A5E03436620-AE
SIPART PS2 (6DR5...)