What slope actually does
A plain rangefinder tells you the straight-line distance to the flag. A sloperangefinder also measures the uphill or downhill angle and gives you an adjusted, "plays like" distance — because a 150-yard shot uphill plays longer than 150 yards, and downhill plays shorter. For a golfer picking a club, that adjusted number is genuinely helpful, which is why slope is a popular feature.
The rule that makes this a real decision
Under the Rules of Golf, measuring plain distance during a round is allowed, but using a device to measure slope-adjusteddistance is not permitted in competition. A slope rangefinder is therefore only tournament-legal if the slope function can be turned off — and visibly seen to be off, so a playing partner can tell. That's why the good slope models have a physical switch with an external indicator, rather than a buried menu setting. We cover the rule in full in are rangefinders legal in golf.
Why a switch is the answer
A slope model with a switch is the best of both worlds: slope on for casual rounds and practice, slope off for club competitions and it's legal. That flexibility is why it's the safe gift for almost any golfer — you don't have to know whether they play tournaments, because the device handles both. If the recipient competes, just make sure the model you choose has that visible external switch rather than only a software toggle.
When non-slope is the better buy
A non-slope rangefinder is cheaper, one less thing to think about, and always legal by design. It's the better pick for a strictly competitive golfer who never wants any doubt, for someone on a tighter budget, or for a golfer whose course is flat enough that elevation barely matters. The trade-off is real on a hilly course, where a non-slope unit simply won't give the "plays like" number that makes club selection easier.
Which to buy as a gift
Buy slope with a switch for most golfers — it covers every situation. Buy non-slopefor a committed competitor, a flat course, or a lower budget. Either way, check the recipient doesn't already own a rangefinder before buying one, and see the rangefinder guidefor the models with live prices. If you're still deciding between a laser and a GPS device entirely, start with GPS watch vs rangefinder.