6 by 4 Hardwood beams, possibly greenheart or oak. I can't confirm but they look like oak to me.
They were decorative beams with notches on the underside which were used on a ceiling but were removed over a decade ago for a more modern look. They have been in the garage since 2013- 14.
1st beam is:
424cm length 15cm height 10cm depth
The 2nd beam was cut in half for a reason which eludes me now so there are 3 beams in total now.
2nd beam is 210cm length
3rd beam is 214cm however there is a notch at the end which is 31cm long so in effect it is a 6 by 4 for 183cm and a 4 by 4 the last 31cm as can be seen in the pictures.