I am by no means an expert. However, S&W made a "10" series of 10mm pistols with model numbers 1006, 1066, 1076, 1026, 1046 and 1086 in various configurations and sizes from mid to full size. I believe the 1006 and 1066 were slide mounted safeties, the 1076 and 1026 were frame mounted decocker models and the 1046 and 1086 were DAO.
The 1006, 1026 and 1046 were full-size with 5" barrels and the others were mid-size.
They were not all produced in the same quantities with some being much harder to come by than others. The 1076 was the model that was up for adoption by the FBI and some are actually marked FBI models on the box. These usually fetch a pretty high price. The 1006 was probably the most common. The 1046 probably the least common.
So the 1026 if that is what you friend has or wants to buy was made in moderate numbers I believe and will be a full-size frame mounted decocker model. A member has one for trade here in the classifieds.
All guns are single stack with mags holding nine rounds of 10mm. All are build like tanks. Some had fixed sights, some had night sights and some adjustable sights.
I've had three models, a customized 1066, a 1006 and a non-FBI 1076. Each was very accurate and a pleasure to shoot.