The BAM XS-B26 is a Chinese copy of the Beeman R9. It is available in 2 calibres: .177, and .22. It is a break barrel type air rifle.

The 26 in B26 is for 26 mm chamber, but it never went in to production at 26 mm.
It is a 25 mm chamber. The Beeman R9 has 26 mm, where the B26 does NOT not have the 26 mm chamber.

Now Bam b26 is 26mm chamber

.177	.22
800 ft/s (243.8 m/s), w/7.9 pellet	650 ft/s (198.1 m/s) w/14.3 pellet