Product identification/recommendation - the goo between sliding door and wooden deck

Question

I'm replacing the lumber of my deck, and need to plan the join between the wooden steps and the sliding door frame. The existing seal seems to be working perfectly, so I'd like to replace with the same thing.

This image is a photo of the existing seal: https://i.sstatic.net/3wAtS.jpg

Does anyone know what this sealant is and/or have product or brand recommendations?
- The wood will be stained, pressure treated deck board (probably Canadian Pine)
- The door frame is powder-coated aluminium
- Temp range from -30 to +30ºC (-22ºF to 90ºF)
- The gap is approximately 3/4 of an inch

Thanks!

Answer 1

its butyl sealant. it still works fine, but nowadays you can use a polyurethane sealant for superior results.