Genitron.com - Review: Ruger P345 Pistol
"Design Notes -
Compared to its P-series siblings, the P345 is a noticeably sleeker pistol. The polymer frame and grip have been extensively slimmed down. Add to this the classic P-series .45 cal single-stack magazine and the P345 grip diameter becomes noticeably and comfortably small in the hand, particularly for a .45 caliber pistol. The slimmed down ambidextrous decock levers and slide-lock lever, as well as the trimmed down rear sight further reduce the pistol's profile."
The single-stack magazine is fully interchangeable with both the P90 and P97 model magazines. With the introduction of the P97 model in 1999, the plastic magazine follower was replaced with a smaller metal follower. This created space in the magazine for an additional cartridge increasing its capacity from 7 to 8 rounds.