The MantisX dry fire and live fire training system.

Such a valuable training aid that you should insist that your pistol features a standard Picatinny style accessory rail.

Because of how important I regard the MantisX, a standard pic rail is one of the more highly valued features in my 9mm Pistol Spreadsheet Shootout. 
BlackbeardX - AR15 Auto-Resetting Dry Fire Training System
Auto-Resetting Trigger Integrated Green or Red Training LaserIntegrated MantisX analyzes your shooting in real timeCompatible with Mantis Laser Academy
94% of shooters improve after using MantisX for just 20 minutes

BlackbeardX - AR15 Auto-Resetting Dry Fire Training System
MantisX10 Elite - Dry Fire , Live Fire, Handgun, Rifle, Shotgun, Archery
MantisX3  - Dry Fire, Live Fire, Handgun, Rifle
MantisX2 - Dry Fire Only, Handgun, Rifle
Mantis Laser Academy
A cheap pistol paired with a MantisX training aid is better than a premium pistol without it. 
Pistols that feature a proprietary rail, like the Sig P365, will need a rail adapter to make use of the MantisX training aid. 
Join the MantisX AmbGun Group for free. The group's goal is to encourage full, ambidextrous operation of firearms, point shooting, and dry fire practice using the MantisX training aid. 
Bonus MantisX Benchmark shootout between Sig P365XL, HK VP9, Springfield Armory Hellcat RDP, Mossberg MC2c, KelTec PF9. 
A must have for any aspiring pistolero, rifle marksman, or airsoft warrior...MantisX. Even better when paired with the Mantis Laser Academy. 
Steady hold factors study using the MantisX to detect muzzle movement during dry firing between AR15 with loop sling and the RDB without a sling.
AR15 vs RDB during adverse wind conditions. Testing using the MantisX.
Training Laser Maintenance Kit380, 9mm, 45ACP, and .40.40 cal will work on 10mm lasers
Shooting offhand, indoors, is the RDB steadier than an AR? MantisX provides the data.
Because gun shot trauma all require the same emergency response whether from 22LR, 9mm, or 45ACP.