I have had good luck with Ring Alarm contact sensors Gen 2 (700 series). They are Z-wave and have a small form factor. I have 6 of them and have not had any problems. The batteries last a long time. They were mentioned by @bcopeland some years ago in a post on his favorite devices.
You don't have to have a Ring hub...they join direct to Hubitat.
Here is a link on how to join them to them to HE.....Support for Ring Alarm Contact Sensor V2? - #8 by bcopeland. May need to include them with S2 so will need a C-7 or C-8.
