The Primary Arms The SLx 3x MicroPrism Red Dot Sight model 710036 and model 710040 are not FFP red dots, that is is a typo. However, the model 710036 has an ACSS reticle designed for use with 5.56/.223 and .308. The model 710040 has an ACSS reticle designed for 7.62x39 and 300 Blackout.
FFP is an error. Model 710036 and 710054 has its reticle 'zeroed' in yards. Model 710038 has a reticle 'zeroed' in meters.
The difference between the two are the distance marks are set for the different calibers.